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Costs of revenue, excluding depreciation and amortization

$ 1,602,900

$ 1,955,800

$ 1,890,200

$ 1,158,200

$ 1,341,900

$ 1,586,200

$ 1,232,400

$ 974,200

$ 6,606,978

$ 5,134,703

$ 4,208,330

1,421,700

1,726,200

1,626,300

971,100

1,120,600

1,369,000

1,068,200

884,400

5,745,307

4,442,125

3,721,303

188,049

164,915

169,662

78,625

Equity in (earnings) losses of unconsolidated affiliates

275,103

261,433

265,910

Interest expense, net

61,011

50,734

48,055

(21,328)

(3,528)

7,978

Other income, net

(12,990)

(6,795)

(15,457)

Provision for income taxes

371,826

225,819

(67,746)

(22,942)

(91,784)

(11,957)

Net income (loss) attributable to non-controlling interests

160,700

64,200

83,300

40,600

55,900

56,500

24,400

(2,900)

348,884

134,035

(79,703)

1,671

2,772

(593)

Basic earnings (loss) per share (in dollars per share)

$ 160,800

$ 63,800

$ 81,700

$ 41,000

$ 53,600

$ 56,300

$ 24,100

$ (2,700)

$ 347,213

^[1]

$ 131,263

^[1]

$ (79,110)

^[1]

Earnings (loss) per share (Note 2):

$ 1.98

$ 0.79

$ 1.01

$ 0.51

$ 0.67

$ 0.70

$ 0.30

$ (0.03)

$ 4.29

$ 1.63

$ (0.98)

Basic weighted average common shares outstanding

80,903

80,372

80,489

Diluted earnings (loss) per share (in dollars per share)

$ 1.95

$ 0.77

$ 0.99

$ 0.50

$ 0.66

$ 0.69

$ 0.30

$ (0.03)

$ 4.22

$ 1.61

$ (0.98)

Diluted weighted average common shares outstanding

82,325

81,394

80,489

[1]	Calculated as total net income (loss) less amounts attributable to non-controlling interests.

Consolidated Statements of Comprehensive Income (Loss) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Statement of Comprehensive Income [Abstract]
Net income (loss)	$ 348,884	$ 134,035	$ (79,703)
Other comprehensive income (loss):
Foreign currency translation gains (losses), net of tax	1,627	2,585	(38,347)
Unrealized gains on equity investee activity, net of tax	475	3,952	0
Comprehensive income (loss)	350,986	140,572	(118,050)
Comprehensive income (loss) attributable to non-controlling interests	1,671	2,772	(593)
Comprehensive income (loss) attributable to MasTec, Inc.	$ 349,315	$ 137,800	$ (117,457)

Consolidated Balance Sheets - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Current assets:
Cash and cash equivalents	$ 40,326	$ 38,767
Accounts receivable, net	1,598,015	1,156,031
Inventories, net	76,992	111,031
Prepaid expenses	101,270	41,548
Other current assets	35,763	55,109
Total current assets	1,852,366	1,402,486
Property and equipment, net	706,506	549,084
Goodwill, net	1,137,738	995,874
Other intangible assets, net	191,142	179,711
Other long-term assets	178,824	55,977
Total assets	4,066,576	3,183,132
Current liabilities:
Current portion of long-term debt	87,866	64,600
Accounts payable	377,954	363,668
Accrued salaries and wages	89,087	67,126
Other accrued expenses	148,971	112,291
Billings in excess of costs and earnings	194,494	161,459
Other current liabilities	65,455	70,846
Total current liabilities	963,827	839,990
Long-term debt	1,280,706	961,379
Deferred income taxes	204,518	166,600
Deferred income taxes		178,355
Other long-term liabilities	184,172	99,774
Total liabilities	2,633,223	2,079,498
Commitments and contingencies (Note 14)
Equity
Preferred stock, $1.00 par value: authorized shares - 5,000,000; issued and outstanding shares – none	0	0
Common stock, $0.10 par value: authorized shares - 145,000,000; issued shares - 90,935,584 and 90,634,771 (including 1,421,041 and 1,927,286 of unvested stock awards) as of December 31, 2017 and December 31, 2016, respectively	9,094	9,063
Capital surplus	775,387	788,914
Retained earnings	857,154	509,941
Accumulated other comprehensive loss	(63,712)	(65,814)
Treasury stock, at cost: 8,132,811 shares and 8,094,004 shares as of December 31, 2017 and 2016, respectively	(147,124)	(145,573)
Total MasTec, Inc. shareholders’ equity	1,430,799	1,096,531
Non-controlling interests	2,554	7,103
Total equity	1,433,353	1,103,634
Total liabilities and equity	$ 4,066,576	$ 3,183,132

Consolidated Balance Sheets (Parenthetical) - $ / shares	Dec. 31, 2017	Dec. 31, 2016
Preferred stock, par value (in dollars per share)	$ 1	$ 1
Preferred stock, shares authorized	5,000,000	5,000,000
Preferred stock, shares issued	0	0
Preferred stock, shares outstanding	0	0
Common stock, par value (in dollars per share)	$ 0.10	$ 0.10
Common stock, shares authorized	145,000,000	145,000,000
Common stock, shares issued	90,935,584	90,634,771
Treasury stock, shares	8,132,811	8,094,004
Common Stock [Member]
Common stock, shares issued	90,935,584	90,634,771
Unvested Stock Awards [Member] \| Common Stock [Member]
Unvested restricted shares (in shares)	1,421,041	1,927,286

Consolidated Statements of Equity - USD ($) $ in Thousands	Total	Common Stock [Member]	Treasury Stock [Member]	Capital Surplus [Member]	Retained Earnings [Member]	Accumulated Other Comprehensive Loss [Member]	Total MasTec, Inc. Shareholders’ Equity [Member]	Non-Controlling Interests [Member]
Beginning balance, common shares outstanding (in shares) at Dec. 31, 2014		87,614,955
Beginning balance at Dec. 31, 2014	$ 1,148,075	$ 8,762	$ (45,573)	$ 756,688	$ 457,788	$ (34,004)	$ 1,143,661	$ 4,414
Beginning balance, treasury shares (in shares) at Dec. 31, 2014			(2,876,311)
Consolidated Statements of Equity
Net income (loss)	(79,703)				(79,110)		(79,110)	(593)
Other comprehensive income (loss)	(38,347)					(38,347)	(38,347)
Non-cash stock-based compensation	12,395			12,395			12,395
Income tax effect from stock-based compensation	(597)			(597)			(597)
Exercise of stock options (in shares)		81,971
Exercise of stock options	544	$ 8		536			544
Issuance of restricted shares (in shares)		446,874
Issuance of restricted shares	0	$ 45		(45)			0
Other stock issuances, net of shares withheld for taxes (in shares)		53,674
Other stock issuances, net of shares withheld for taxes	1,024	$ 5		1,019			1,024
Acquisition of treasury stock, at cost (in shares)			(5,217,693)
Acquisition of treasury stock, at cost	(100,000)		$ (100,000)				(100,000)
Ending balance, common shares outstanding (in shares) at Dec. 31, 2015		88,197,474
Ending balance at Dec. 31, 2015	943,391	$ 8,820	$ (145,573)	769,996	378,678	(72,351)	939,570	3,821
Ending balance, treasury shares (in shares) at Dec. 31, 2015			(8,094,004)
Consolidated Statements of Equity
Net income (loss)	134,035				131,263		131,263	2,772
Other comprehensive income (loss)	6,537					6,537	6,537
Non-cash stock-based compensation	15,072			15,072			15,072
Income tax effect from stock-based compensation	(107)			(107)			(107)
Exercise of stock options (in shares)		202,700
Exercise of stock options	2,053	$ 20		2,033			2,053
Issuance of restricted shares (in shares)		2,115,672
Issuance of restricted shares	0	$ 212		(212)			0
Other stock issuances, net of shares withheld for taxes (in shares)		118,925
Other stock issuances, net of shares withheld for taxes	2,143	$ 11		2,132			2,143
Other activity, net	$ 510						0	510
Ending balance, common shares outstanding (in shares) at Dec. 31, 2016	90,634,771	90,634,771
Ending balance at Dec. 31, 2016	$ 1,103,634	$ 9,063	$ (145,573)	788,914	509,941	(65,814)	1,096,531	7,103
Ending balance, treasury shares (in shares) at Dec. 31, 2016	(8,094,004)		(8,094,004)
Consolidated Statements of Equity
Net income (loss)	$ 348,884				347,213		347,213	1,671
Other comprehensive income (loss)	2,102					2,102	2,102
Non-cash stock-based compensation	15,656			15,656			15,656
Issuance of restricted shares (in shares)		393,570
Issuance of restricted shares	0	$ 39		(39)			0
Shares withheld for taxes, net of other share activity (in shares)		(92,757)
Shares withheld for taxes, net of other share activity	(3,085)	$ (8)		(3,077)			(3,085)
Acquisition of treasury stock, at cost (in shares)			(38,807)
Acquisition of treasury stock, at cost	(1,551)		$ (1,551)				(1,551)
Distributions to non-controlling interests	(1,280)						0	(1,280)
Purchase of non-controlling interests	$ (31,007)			(26,067)			(26,067)	(4,940)
Ending balance, common shares outstanding (in shares) at Dec. 31, 2017	90,935,584	90,935,584
Ending balance at Dec. 31, 2017	$ 1,433,353	$ 9,094	$ (147,124)	$ 775,387	$ 857,154	$ (63,712)	$ 1,430,799	$ 2,554
Ending balance, treasury shares (in shares) at Dec. 31, 2017	(8,132,811)		(8,132,811)

Consolidated Statements of Cash Flows - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Cash flows from operating activities:
Net income (loss)	$ 348,884	$ 134,035	$ (79,703)
Adjustments to reconcile net income (loss) to net cash provided by operating activities:
Depreciation and amortization	188,049	164,915	169,662
Goodwill and intangible asset impairment	0	0	78,625
Non-cash interest expense, net	3,100	2,994	2,633
Non-cash stock-based compensation expense	15,656	15,072	12,395
Provision for (benefit from) deferred income taxes	18,277	(3,935)	3,925
Equity in (earnings) losses of unconsolidated affiliates	(21,328)	(3,528)	7,978
(Gains) losses on sales of assets, net, including fixed assets held-for-sale	(5,935)	1,957	(8,191)
Other non-cash items, net	7,222	4,700	1,480
Changes in assets and liabilities, net of acquisitions:
Accounts receivable	(417,491)	(246,419)	362,275
Inventories	36,187	(22,232)	22,356
Other assets, current and long-term portion	(117,091)	44,650	(11,241)
Accounts payable and accrued expenses	54,342	66,078	(162,441)
Billings in excess of costs and earnings	46,075	12,131	(5,085)
Book overdrafts	(10,459)	4,069	4,699
Other liabilities, current and long-term portion	10,775	31,106	(31,954)
Net cash provided by operating activities	156,263	205,593	367,413
Cash flows from investing activities:
Cash paid for acquisitions, net of cash acquired	(115,995)	(4,102)	(148)
Capital expenditures	(123,412)	(117,114)	(84,410)
Proceeds from sale of property and equipment	19,963	11,239	13,932
Payments for other investments	(77,105)	(32,169)	(127,480)
Proceeds from other investments	23,801	1,125	69,406
Net cash used in investing activities	(272,748)	(141,021)	(128,700)
Cash flows from financing activities:
Proceeds from credit facilities	2,699,047	1,681,424	1,702,431
Repayments of credit facilities	(2,457,293)	(1,627,129)	(1,742,077)
Repayments of other borrowings, net	(3,350)	(10,694)	(13,843)
Payments of capital lease obligations	(67,740)	(57,980)	(57,095)
Payments of acquisition-related contingent consideration	(18,843)	(19,822)	(47,523)
Payments to non-controlling interests, including acquisition of interests and distributions	(22,728)	0	0
(Payments for) proceeds from stock-based awards, net	(3,085)	4,200	1,566
Repurchase of common stock	(1,552)	0	(100,000)
Other financing activities, net	(6,301)	515	(2,379)
Net cash provided by (used in) financing activities	118,155	(29,486)	(258,920)
Effect of currency translation on cash	(111)	(1,303)	1,132
Net increase (decrease) in cash and cash equivalents	1,559	33,783	(19,075)
Cash and cash equivalents - beginning of period	38,767	4,984	24,059
Cash and cash equivalents - end of period	40,326	38,767	4,984
Supplemental cash flow information:
Interest paid	59,157	47,698	47,405
Income taxes paid, net of refunds	78,653	59,342	2,536
Supplemental disclosure of non-cash information:
Equipment acquired under capital lease and financing arrangements	150,055	25,092	23,817
Accrued capital expenditures	4,716	1,582	3,164
Earn-Out Liabilities [Member]
Supplemental disclosure of non-cash information:
Additions to acquisition-related contingent consideration	$ 102,534	$ 0	$ 0

Business, Basis of Presentation and Significant Accounting Policies	12 Months Ended
	Dec. 31, 2017
Accounting Policies [Abstract]
Business, Basis of Presentation and Significant Accounting Policies	Note 1 – Business, Basis of Presentation and Significant Accounting Policies Nature of the Business MasTec, Inc. (collectively with its subsidiaries, “MasTec” or the “Company”) is a leading infrastructure construction company operating mainly throughout North America across a range of industries. The Company’s primary activities include the engineering, building, installation, maintenance and upgrade of communications, energy and utility infrastructure, such as: wireless, wireline/fiber, install-to-the-home and customer fulfillment activities; petroleum and natural gas pipeline infrastructure; electrical utility transmission and distribution; power generation; heavy civil; and industrial infrastructure. MasTec’s customers are primarily in these industries. MasTec reports its results under five reportable segments: (1) Communications; (2) Oil and Gas; (3) Electrical Transmission; (4) Power Generation and Industrial; and (5) Other. Principles of Consolidation The accompanying consolidated financial statements include MasTec, Inc. and its subsidiaries and include the accounts of all majority owned subsidiaries over which the Company exercises control and, when applicable, entities in which the Company has a controlling financial interest. All significant intercompany balances and transactions have been eliminated in consolidation. Other parties’ interests in entities that MasTec consolidates are reported as non-controlling interests within equity. Net income or loss attributable to non-controlling interests is reported as a separate line item below net income or loss. The Company’s investments in entities for which the Company does not have a controlling interest, but for which it has the ability to exert significant influence, are accounted for using the equity method of accounting. Equity method investments are recorded as other long-term assets. Income or loss from these investments is recorded as a separate line item in the statements of operations. Intercompany profits or losses associated with the Company’s equity method investments are eliminated until realized by the investee in transactions with third parties. For equity investees in which the Company has an undivided interest in the assets, liabilities and profits or losses of an unincorporated entity, but the Company does not exercise control over the entity, the Company consolidates its proportional interest in the accounts of the entity. The cost method is used for investments in entities for which the Company does not have the ability to exert significant influence. Certain prior year amounts have been reclassified to conform to the current period presentation. Management determines whether each business entity in which it has equity interests, debt, or other investments constitutes a variable interest entity (“VIE”) based on the nature and characteristics of such arrangements. If an investment arrangement is determined to be a VIE, then management determines if the Company is the VIE’s primary beneficiary by evaluating several factors, including the Company’s: (i) risks and responsibilities; (ii) ownership interests; (iii) decision making powers; and (iv) financial interests, among other factors. If management determines the Company is the primary beneficiary of a VIE, then it would be consolidated, and other parties’ interests in the VIE would be accounted for as non-controlling interests. The primary beneficiary consolidating the VIE must normally have both (i) the power to direct the primary activities of the VIE and (ii) the obligation to absorb losses of the VIE or the right to receive benefits from the VIE, which, in either case, could be significant to the VIE. As of December 31, 2017, the Company determined that certain of its investment arrangements were VIEs; however, because it does not have the power to direct the primary activities that most significantly impact the economic performance of these VIEs, the Company is not the primary beneficiary, and accordingly, has not consolidated these VIEs. Translation of Foreign Currencies The assets and liabilities of foreign subsidiaries with a functional currency other than the U.S. dollar are translated into U.S. dollars at period-end exchange rates, with resulting translation gains or losses accumulated within other comprehensive income or loss. Revenue and expenses are translated into U.S. dollars at average rates of exchange during the applicable period. Substantially all of the Company’s foreign operations use their local currency as their functional currency. Currency gains or losses resulting from transactions executed in currencies other than the functional currency are included in other income or expense, net. In these consolidated financial statements, “$” means U.S. dollars unless otherwise noted. Management Estimates The preparation of consolidated financial statements in accordance with U.S. GAAP requires the use of estimates and assumptions that affect the amounts reported in the consolidated financial statements and accompanying notes. These estimates are based on historical experience and various other assumptions, the results of which form the basis of making judgments about the Company’s operating results and the carrying values of assets and liabilities that are not readily apparent from other sources. Key estimates include: the recognition of revenue and project profit or loss, which the Company defines as project revenue, less project costs of revenue, including project-related depreciation, in particular, on construction contracts accounted for under the percentage-of-completion method, for which the recorded amounts require estimates of costs to complete and the amount of probable contract price adjustments; allowances for doubtful accounts; fair value estimates, including those related to business acquisitions, valuations of goodwill and intangible assets, acquisition-related contingent consideration and equity investments; asset lives used in computing depreciation and amortization; fair values of financial instruments; self-insurance liabilities; other accruals and allowances; income taxes; and the estimated effects of litigation and other contingencies. While management believes that such estimates are reasonable when considered in conjunction with the Company’s consolidated financial position and results of operations taken as a whole, actual results could differ materially from those estimates. Significant Accounting Policies The following is a summary of significant accounting policies followed in the preparation of the accompanying consolidated financial statements. Revenue Recognition Revenue is derived from construction projects performed under master and other service agreements as well as from contracts for specific projects or jobs requiring the construction and installation of an entire infrastructure system or specified units within an entire infrastructure system. The Company frequently provides services under unit price or fixed price master service or other service agreements. Revenue and related costs for master and other service agreements billed on a time and materials basis are recognized as the services are rendered. Revenue derived from projects performed under master service and other service agreements totaled 36%, 43% and 48% of consolidated revenue for the years ended December 31, 2017, 2016 and 2015, respectively. The Company also performs services under master and other service agreements on a fixed fee basis, under which MasTec furnishes specified units of service for a fixed price per unit of service and revenue is recognized as the services are rendered. Revenue from fixed price contracts provides for a fixed amount of revenue for the entire project, subject to certain additions for changed scope or specifications. Revenue from these contracts, as well as for certain projects pursuant to master and other service agreements, is recognized using the percentage-of-completion method, under which the percentage of revenue to be recognized for a given project is measured by the percentage of costs incurred to date on the contract to the total estimated costs for the contract. Such contracts provide that the customer accept completion of progress to date and compensate the Company for services rendered, which may be measured in terms of costs incurred, units installed, hours expended or some other measure of progress. Contract costs include all direct materials, labor and subcontracted costs and those indirect costs related to contract performance, such as indirect labor, supplies, tools, repairs and the operational costs of capital equipment. Much of the materials associated with the Company’s work are customer-furnished and are therefore not included in contract revenue and costs. The estimation process for revenue recognized under the percentage-of-completion method is based on the professional knowledge and experience of the Company’s project managers, engineers and financial professionals. Management reviews estimates of contract revenue and costs on an ongoing basis. Changes in job performance, job conditions and management’s assessment of expected contract settlements are factors that influence estimates of total contract value and total costs to complete those contracts and, therefore, the Company’s profit recognition. Changes in these factors may result in revisions to costs and income, and their effects are recognized in the period in which the revisions are determined, which could materially affect the Company’s results of operations in the period in which such changes are recognized. For both the years ended December 31, 2017 and 2016, project profit was affected by less than 5% as a result of changes in contract estimates included in projects that were in process as of December 31, 2016 and 2015, respectively. Provisions for losses on uncompleted contracts are made in the period in which such losses are determined to be probable and the amount can be reasonably estimated. The majority of fixed price contracts are completed within one year. The Company may incur costs subject to change orders, whether approved or unapproved by the customer, and/or claims related to certain contracts. Management determines the probability that such costs will be recovered based upon engineering studies and legal opinions, past practices with the customer, specific discussions, correspondence or preliminary negotiations with the customer. The Company treats such costs as a cost of contract performance in the period incurred if it is not probable that the costs will be recovered, and defers costs or recognizes revenue up to the amount of the related cost if it is probable that the contract price will be adjusted and can be reliably estimated. As of December 31, 2017 and 2016, the Company had approximately $146 million and $17 million, respectively, of change orders and/or claims that had been included as contract price adjustments on certain contracts that were in the process of being resolved in the normal course of business, including through negotiation, arbitration and other proceedings. These contract price adjustments, which are included within costs and earnings in excess of billings or billed accounts receivable, as appropriate, represent management’s best estimate of contract revenue that has been earned and that management believes is probable of collection. As of both December 31, 2017 and 2016, these change orders were primarily related to contracts in the Oil and Gas segment. Revenue related to unapproved change orders totaled approximately $142 million and $4 million, respectively, for the years ended December 31, 2017 and 2016. The Company actively engages in substantive meetings with its customers to complete the final approval process, and generally expects these processes to be completed within one year. The amounts ultimately realized upon final acceptance by its customers could be higher or lower than such estimated amounts. Billings In Excess of Costs and Earnings (“BIEC”) on uncompleted contracts is classified within current liabilities. Costs and Earnings In Excess of Billings (“CIEB”), which is also referred to as work in process, is classified within current assets. Work in process on contracts is based on work performed but not yet billed to customers as per individual contract terms. Allowance for Doubtful Accounts The Company maintains an allowance for doubtful accounts for estimated losses resulting from the inability of its customers to make required payments. Management analyzes the collectibility of trade accounts receivable and the adequacy of the allowance for doubtful accounts on a regular basis taking into consideration the aging of account balances, historical bad debt experience, customer concentrations, customer credit-worthiness, customer financial condition and credit reports, availability of mechanics’ and other liens, existence of payment bonds and other sources of payment and the current economic environment. The Company establishes an allowance for doubtful accounts for anticipated losses of its business units when a business unit has historical experience of losses that are considered to be ordinary course. In addition, an allowance is established when it is probable that a specific receivable is not collectible and the loss can be reasonably estimated. Amounts are written off against the allowance when they are considered to be uncollectible. If estimates of the collectibility of accounts receivable change, or should customers experience unanticipated financial difficulties, or if anticipated recoveries in existing bankruptcies or other work-out situations fail to materialize, additional allowances may be required. Estimates of collectibility are subject to significant change during times of economic weakness or uncertainty in either the overall economy or within the industries served by MasTec. Management actively monitors the economic environment and its impact on MasTec’s customers in connection with its evaluation of the Company’s accounts receivable portfolio and the adequacy of its allowance for doubtful accounts. Cash and Cash Equivalents Cash consisting of interest-bearing demand deposits is carried at cost, which approximates fair value. All highly liquid investments purchased with an original maturity of three months or less are considered to be cash equivalents, which are carried at fair value. On a daily basis, available funds are swept from the Company’s depository accounts into a concentration account and used to repay outstanding revolving loans under the Company’s senior secured credit facility. Cash balances maintained by certain operating subsidiaries and by entities that are proportionately consolidated that are not swept into the concentration account, as well as deposits made subsequent to the daily cash sweep, are classified as cash. Included in the Company’s cash balances as of December 31, 2017 and 2016 are amounts held by entities that are proportionately consolidated totaling $17.3 million and $7.7 million, respectively. These amounts are available to support the operations of those entities, but are not available for the Company’s other operations. The Company generally does not fund its disbursement accounts for checks it has written until the checks are presented to the bank for payment. Outstanding checks that have not yet cleared through the banking system represent book overdrafts, which are classified within accounts payable. There are no compensating balance requirements associated with the Company’s depository accounts and there are no other restrictions on the transfer of cash associated with the Company’s depository accounts. As of December 31, 2017 and 2016, book overdrafts totaled $30.0 million and $39.9 million, respectively. Inventories Inventories consist of materials and supplies for construction and installation projects, which are valued at the lower of cost or net realizable value using either the average cost or specific identification methods of costing. For materials or supplies purchased on behalf of specific customers or projects, loss of the customer or cancellation of the project could result in an impairment of the value of materials purchased. Technological or market changes can also render certain materials obsolete. Allowances for inventory obsolescence are determined based upon specific facts and circumstances and market conditions. As of December 31, 2017 and 2016, inventory obsolescence reserves were $7.7 million and $3.5 million, respectively. Long-Lived Assets The Company’s long-lived assets consist primarily of property and equipment and finite-lived intangible assets. Property and equipment are recorded at cost, or, if acquired in a business combination, at the acquisition date fair value. Certain costs incurred in connection with developing or obtaining internal-use software are capitalized within office furniture and equipment. Depreciation and amortization of long-lived assets is computed using the straight-line method over the estimated useful lives of the respective assets. Leasehold improvements are depreciated over the shorter of the term of the lease or the estimated useful lives of the improvements. Property and equipment under capital leases are depreciated over their estimated useful lives. Expenditures for repairs and maintenance are charged to expense as incurred. Expenditures for betterments and major improvements are capitalized and depreciated over the remaining useful lives of the assets. The carrying amounts of assets sold or retired and the related accumulated depreciation are eliminated in the year of disposal, with resulting gains or losses included in other income or expense. When the Company identifies assets to be sold, those assets are valued based on their estimated fair value less costs to sell, classified as held-for-sale and depreciation is no longer recorded. Estimated losses on disposal are included within other expense. Acquired intangible assets that have finite lives are amortized over their useful lives, which are generally based on contractual or legal rights. Finite-lived intangible assets are amortized in a manner consistent with the pattern in which the related benefits are expected to be consumed. Management reviews long-lived assets for impairment whenever events or changes in circumstances indicate that their carrying amounts may not be recoverable. If an evaluation is required, the estimated future undiscounted cash flows associated with the asset are compared with the asset’s carrying amount to determine if there has been an impairment, which is calculated as the difference between the fair value of an asset and its carrying value. Estimates of future undiscounted cash flows are based on expected growth rates for the business, anticipated future economic conditions and estimates of residual values. Fair values take into consideration management’s estimates of risk-adjusted discount rates, which are believed to be consistent with assumptions that marketplace participants would use in their estimates of fair value. Other than certain asset write-downs as discussed within “Restructuring Activities” within this Significant Accounting Policies section, for the three years in the period ended December 31, 2017, there were no material impairment charges associated with long-lived assets. Goodwill and Indefinite-Lived Intangible Assets The Company has goodwill and certain indefinite-lived intangible assets that have been recorded in connection with its acquisitions of businesses. Goodwill and indefinite-lived intangible assets are not amortized, but instead are tested for impairment at least annually. The Company performs its annual impairment tests of goodwill and indefinite-lived intangible assets during the fourth quarter of each year, and on a quarterly basis, management monitors these assets for potential impairment triggers. Goodwill is required to be tested for impairment at the reporting unit level. A reporting unit is an operating segment or one level below the operating segment level, which is referred to as a component. Management identifies its reporting units by assessing whether components (i) have discrete financial information available; (ii) engage in business activities; and (iii) have a segment manager regularly review the component’s operating results. Net assets and goodwill of acquired businesses are allocated to the reporting unit associated with the acquired business based on the organizational structure of the combined entities. If two or more components are deemed economically similar, those components are aggregated into one reporting unit when performing the annual goodwill impairment review. Other than the Company’s Electrical Transmission operating segment, and, beginning in 2017, one reporting unit within the Company’s Power Generation and Industrial operating segment, each of the Company’s reporting units comprises one component. For each of the three years in the period ended December 31, 2017, the Company combined the components of its Electrical Transmission operating segment, and, for the year ended December 31, 2017, combined two components within the Power Generation and Industrial operating segment, into one reporting unit based on review of the components’ operations, which indicated economic similarities and shared operational, sales and general and administrative resources across those components. For each of the three years in the period ended December 31, 2017, management performed a qualitative assessment for its goodwill and indefinite-lived intangible assets by examining relevant events and circumstances that could have an effect on their fair values, such as: macroeconomic conditions, industry and market conditions, entity-specific events, financial performance and other relevant factors or events that could affect earnings and cash flows. 2017 Assessment. Based on the results of the qualitative assessments for the year ended December 31, 2017, quantitative testing was performed for the Company’s Electrical Transmission operating segment, for one reporting unit in the Company’s Power Generation and Industrial operating segment, and for two reporting units within the Oil and Gas operating segment due to a combination of lower than expected success rates on new project awards, certain market conditions, including market project deferrals, and reduced levels of operating productivity. For these reporting units, management performed a two-step quantitative goodwill impairment test. Management estimated their respective fair values using a combination of market and income approaches. Under the market approach, fair values were estimated using published market multiples for comparable companies. Under the income approach, a discounted cash flow methodology was used, including: (i) management estimates, such as projections of revenue, operating costs and cash flows, taking into consideration historical and anticipated financial results; (ii) general economic and market conditions; and (iii) the impact of planned business and operational strategies. Estimated discount rates were determined using the Company’s average cost of capital at the time of the analysis, taking into consideration the risks inherent within each reporting unit individually, which are greater than the risks inherent in the Company as a whole. In 2017, significant assumptions used in testing the reporting units included terminal values based on a terminal growth rate of 3.5%, five to nine years of discounted cash flows prior to the terminal value, and discount rates ranging from 13.0% to 15.5%. Management believes the assumptions used in its quantitative goodwill impairment tests are reflective of the risks inherent in the business models of its reporting units and within its industry. Based on the results of the quantitative assessment, the estimated fair values of the Electrical Transmission operating segment and the reporting unit in the Power Generation and Industrial operating segment were determined to substantially exceed their carrying values. Additionally, the two reporting units in the Oil and Gas segment, which have approximately $65 million and $15 million of goodwill, had estimated fair values in excess of their carrying values by approximately 10% and 19%, respectively. A 100 basis point increase in the discount rate would not have resulted in the reporting units’ carrying values exceeding their fair values. Management also performed quantitative testing during 2017 for indefinite-lived pre-qualification intangible assets in the Oil and Gas and Electrical Transmission operating segments. Management estimated the fair values of these intangible assets using a cost methodology, incorporating estimates of the opportunity cost associated with the assets’ loss based on discounted cash flows over a two to four-year period. The impairment tests incorporated estimated discount rates ranging from 13.0% to 14.0%. Based on the results of this assessment, management determined that the estimated fair value of the indefinite-lived pre-qualification intangible asset in the Oil and Gas operating segment, which has a carrying value of approximately $45 million, exceeded its carrying value by approximately 19%, and a 100 basis point increase in the discount rate would not have resulted in this asset’s carrying value exceeding its fair value. The estimated fair value of the indefinite-lived pre-qualification intangible asset in the Electrical Transmission operating segment was determined to substantially exceed its carrying value. Management also performed quantitative testing during 2017 for an indefinite-lived trade name intangible asset in the Power Generation and Industrial operating segment. Management estimated the fair value of the intangible asset using an income approach, incorporating estimates of discounted cash flows over a five-year period prior to the terminal value. The impairment test incorporated an estimated discount rate of 14%. Based on the results of this assessment, management determined that the estimated fair value of the indefinite-lived trade name intangible asset in the Power Generation and Industrial operating segment substantially exceeded its carrying value. 2016 Assessment. Based on the qualitative assessments for the year ended December 31, 2016, quantitative testing was performed for two reporting units within the Oil and Gas operating segment and for the Electrical Transmission operating segment. Management performed a two-step quantitative goodwill impairment test and estimated their respective fair values using a combination of market and income approaches. In 2016, significant assumptions used in testing the reporting units included terminal values based on terminal growth rates ranging from 3.0% to 3.5%, nine years of discounted cash flows prior to the terminal value, and discount rates ranging from 13.0% to 14.5%, which management believes were reflective of the risks inherent in the business models of its reporting units and within its industry. In 2016, the estimated fair value of the Electrical Transmission operating segment exceeded its carrying value by approximately 5%. A 100 basis point increase in the discount rate would have resulted in the Electrical Transmission operating segment carrying value exceeding fair value. As of December 31, 2016, the Electrical Transmission operating segment had approximately $150 million of goodwill. Additionally, as of December 31, 2016, for one of the reporting units in the Oil and Gas operating segment for which a quantitative impairment test was performed, the estimated fair value exceeded its carrying value by approximately 11%, and a 100 basis point increase in the discount rate would not have resulted in the reporting unit’s carrying value exceeding its fair value. This reporting unit has approximately $15 million of goodwill. The estimated fair value of the other reporting unit in the Oil and Gas segment for which a quantitative impairment test was performed was determined to substantially exceed its carrying value. Management also performed quantitative testing during 2016 for an indefinite-lived pre-qualification intangible asset in the Oil and Gas operating segment and for an indefinite-lived pre-qualification intangible asset in the Electrical Transmission operating segment. Management estimated fair values using a cost methodology, incorporating estimates of the opportunity cost associated with the assets’ loss based on discounted cash flows over a two to three-year period. The impairment tests incorporated estimated discount rates ranging from 13.0% to 13.5%. For the indefinite-lived pre-qualification intangible assets in the Oil and Gas and Electrical Transmission operating segments, the estimated fair values substantially exceeded their carrying values. 2015 Assessment. Based on the qualitative assessments for the year ended December 31, 2015, quantitative testing was performed for four reporting units, three in the Oil and Gas operating segment and for the Electrical Transmission operating segment. Significant assumptions used in testing the reporting units included terminal values based on terminal growth rates ranging from 3.0% to 3.5%, nine years of discounted cash flows prior to the terminal value, and discount rates ranging from 12.0% to 14.0%. In 2015, the estimated fair value of one reporting unit in the Oil and Gas operating segment was determined to be less than its carrying value and the second step of the goodwill impairment test was performed. The implied fair value of this reporting unit’s goodwill was compared with its carrying value and a pre-tax, non-cash impairment charge of $68.5 million was recorded for the difference. This reporting unit had $11.2 million of goodwill remaining at December 31, 2015. In 2015, the estimated fair value of the Electrical Transmission operating segment exceeded its carrying value by approximately 5%. A 100 basis point change in the discount rate would have resulted in the Electrical Transmission operating segment carrying value exceeding fair value. The estimated fair values of all other reporting units for which quantitative impairment tests were performed for the year ended December 31, 2015 were determined to substantially exceed their carrying values. A 100 basis point change in the discount rate would not have had a material impact on the results of these impairment tests as of the date the testing was performed. Management also performed quantitative testing during 2015 for two indefinite-lived pre-qualification intangible assets within the Oil and Gas operating segment and one indefinite-lived pre-qualification intangible asset within the Electrical Transmission operating segment. Management estimated fair values using a cost methodology, incorporating estimates of the opportunity cost associated with the assets’ loss based on discounted cash flows over a two to three-year period. The impairment tests incorporated estimated discount rates ranging from 12.0% to 14.0%. For one of the indefinite-lived pre-qualification intangible assets within the Oil and Gas operating segment, the carrying value of the asset exceeded its estimated fair value and a pre-tax, non-cash impairment charge of $10.1 million was recorded for the difference. The adjusted carrying value of this pre-qualification asset was approximately $20.5 million at December 31, 2015. For the other indefinite-lived pre-qualification assets for which quantitative testing was performed during 2015, the estimated fair values substantially exceeded their carrying values. As of December 31, 2017 and 2016, management believes that its recorded balances of goodwill and indefinite-lived intangible assets are recoverable; however, significant changes in the assumptions or estimates used in the Company’s impairment analyses, such as a reduction in profitability and/or cash flows, could result in non-cash goodwill and indefinite-lived intangible asset impairment charges in future periods. Valuation of Net Assets Acquired and Earn-Out Liabilities The determination of the fair value of net assets acquired in a business combination requires estimates and judgments of future cash flow expectations for the acquired business and the related identifiable tangible and intangible assets. Fair values are calculated using expected cash flows and industry-standard valuation techniques. For current assets and current liabilities, book value is generally assumed to equal fair value. Goodwill is the amount by which consideration paid exceeds the fair value of acquired net assets. Acquisition costs, including acquisition integration costs, are expensed as incurred and are included within general and administrative expenses in the consolidated statements of operations. Consideration paid generally consists of cash, common stock and potential future payments that are contingent upon the acquired business achieving certain levels of earnings in the future, also referred to as “acquisition-related contingent consideration” or “earn-out” payments. Earn-out liabilities are measured at their estimated fair value as of the date of acquisition, with subsequent changes in fair value recorded within other income or expense in the consolidated statements of operations. Fair value as of the date of acquisition is estimated based on projections of expected future cash flows of the acquired business. Subsequent to the date of acquisition, if future earn-out payments are expected to exceed earn-out payments estimated as of the date of acquisition, then a loss would be recognized in the period in which that expectation is considered probable. Conversely, if future earn-out payments are expected to be less than earn-out payments estimated as of the date of acquisition, a gain would be recognized in the period in which that expectation is considered probable. Acquisition-related contingent consideration is included within other current and other long-term liabilities, as appropriate, within the consolidated balance sheets. Due to the time required to gather and analyze the necessary data for each acquisition, U.S. GAAP provides a “measurement period” of up to one year in which to finalize these fair value determinations. During the measurement period, preliminary fair value estimates may be revised if new information is obtained about the facts and circumstances existing as of the date of acquisition based on the final net assets and net working capital of the acquired business, as prescribed in the applicable purchase agreements. Such adjustments may result in the recognition of, or adjust the fair values of, acquisition-related assets and liabilities and/or consideration paid. For the year ended December 31, 2017, measurement period adjustments included certain adjustments to the preliminary estimates of intangible assets and acquisition-related contingent consideration, and resulted in a net increase of approximately $2.7 million in estimated goodwill for businesses acquired in 2017. Fair value adjustments resulting from circumstances that developed after the date of acquisition are reflected as income or expense, as appropriate, in the period the adjustment is considered probable. Fair Value of Financial Instruments The Company’s financial instruments include cash and cash equivalents, accounts and notes receivable, cash collateral deposited with insurance carriers, life insurance assets, equity investments, deferred compensation plan assets and liabilities, accounts payable and other current liabilities, acquisition-related contingent consideration and debt obligations. Fair value is the price that would be received to sell an asset or paid to transfer a liability (an exit price) in the principal or most advantageous market for the asset or liability in an orderly transaction between market participants on the measurement date. The fair value guidance establishes a valuation hierarchy, which requires maximizing the use of observable inputs when measuring fair value. The three levels of inputs that may be used are: (i) Level 1 - quoted market prices in active markets for identical assets or liabilities; (ii) Level 2 - observable market-based inputs or other observable inputs; and (iii) Level 3 - significant unobservable inputs that cannot be corroborated by observable market data, which are generally determined using valuation models incorporating management estimates of market participant assumptions. In instances in which the inputs used to measure fair value fall into different levels of the fair value hierarchy, the fair value measurement classification is determined based on the lowest level input that is significant to the fair value measurement in its entirety. Management’s assessment of the significance of a particular item to the fair value measurement in its entirety requires judgment, including the consideration of inputs specific to the asset or liability. Fair values of financial instruments are estimated using public market prices, quotes from financial institutions and other available information. Due to their short-term maturity, the carrying amounts of cash and cash equivalents, accounts receivable, accounts payable and other current liabilities approximate their fair values. Management believes the carrying values of notes and other receivables, cash collateral deposited with insurance carriers, deferred compensation plan assets and liabilities and outstanding balances on its credit facilities approximate their fair values. Deferred Financing Costs Deferred financing costs relate to the Company’s debt instruments, the short and long-term portions of which are reflected as a deduction from the carrying amount of the related debt instrument, including the Company’s credit facility. Deferred financing costs are amortized over the terms of the related debt instruments using the effective interest method. For the year ended December 31, 2017, deferred financing costs totaled $6.3 million. Deferred financing costs were de minimis in 2016, and for the year ended December 31, 2015, totaled $2.4 million. Amortization expense associated with deferred financing costs, which is included within interest expense, net, totaled $3.3 million, $3.2 million and $2.9 million for the years ended December 31, 2017, 2016 and 2015. Deferred financing costs, net of accumulated amortization, totaled $13.0 million and $9.8 million as of December 31, 2017 and 2016, respectively. Self-Insurance The Company is self-insured up to the amount of its deductible for its insurance policies. MasTec maintains insurance policies subject to per claim deductibles of $1.5 million for its workers’ compensation policy, $3.0 million for its general liability policy and $3.0 million for its automobile liability policy. The Company has excess umbrella coverage up to $100.0 million per claim and in the aggregate. Liabilities under these insurance programs are accrued based upon management’s estimates of the ultimate liability for claims reported and an estimate of claims incurred but not reported, with assistance from third-party actuaries. MasTec also maintains an insurance policy with respect to employee group medical claims, which is subject to annual per employee maximum losses of $0.5 million. MasTec’s liability for employee group medical claims is based on statistical analysis of historical claims experience and specific knowledge of actual losses that have occurred. The Company is also required to post letters of credit and provide cash collateral to certain of its insurance carriers and to obtain surety bonds in certain states. Cash collateral deposited with insurance carriers is included in other long-term assets in the consolidated balance sheets. The present value of the Company’s self-insurance liability is reflected in the consolidated balance sheets within current and other long-term liabilities, as appropriate. The determination of such claims and expenses and the appropriateness of the related liability is reviewed and updated quarterly, however, these insurance liabilities are difficult to assess and estimate due to unknown factors, including the severity of an injury, the determination of the Company’s liability in proportion to other parties and the number of incidents not reported. Accruals are based upon known facts and historical trends. Although management believes its accruals are adequate, a change in experience or actuarial assumptions could materially affect the Company’s results of operations in a particular period. Income Taxes The Company records income taxes using the asset and liability method of accounting for deferred income taxes. Under this method, deferred tax assets and liabilities are recognized for the expected future tax consequence of temporary differences between the financial statement and income tax basis of the Company’s assets and liabilities. Income taxes are estimated in each of the jurisdictions in which the Company operates. This process involves estimating the tax exposure, together with assessing temporary differences resulting from differing treatment of items, such as deferred revenue, for tax and accounting purposes. These differences result in deferred tax assets and liabilities, which are included within the consolidated balance sheets as net long-term assets and/or liabilities, as appropriate. The recording of a deferred tax asset assumes the realization of such asset in the future. Otherwise, a valuation allowance is recorded to reduce the asset to its estimated net realizable value. If management determines that the Company may not be able to realize all or part of a deferred tax asset in the future, a valuation allowance for the deferred tax asset is charged to income tax expense in the period the determination is made. Management considers future pretax income and ongoing prudent and feasible tax planning strategies in assessing the estimated net realizable value of tax assets and the corresponding need for a valuation allowance. The Company adopted Accounting Standards Update 2015-17, Income Taxes (Topic 740): Balance Sheet Classification of Deferred Taxes (“ASU 2015-17”) effective January 1, 2017, which changed the classification requirements for deferred tax assets and liabilities. ASU 2015-17 requires long-term classification of all deferred tax assets and liabilities, rather than separately classifying deferred tax assets and liabilities based on their net current and non-current amounts, as was required under the previous guidance. The adoption of ASU 2015-17, which was adopted on a prospective basis, did not have a material effect on the Company’s consolidated financial statements. In determining the provision for income taxes, management uses an effective tax rate based on annual pre-tax income, statutory tax rates, permanent tax differences and tax planning opportunities in the various jurisdictions in which the Company operates. Significant factors that affect the annual effective tax rate include management’s assessment of certain tax matters, the location and amount of taxable earnings, changes in certain non-deductible expenses and expected credits. In December 2017, the 2017 Tax Act was enacted, which includes broad tax reforms that are applicable to the Company. Under the provisions of the 2017 Tax Act, the U.S. corporate tax rate decreased from 35% to 21% effective January 1, 2018. As a result, the Company’s U.S. deferred income tax balances were required to be remeasured in 2017. The Company completed an initial remeasurement of its deferred tax assets and liabilities as of December 31, 2017 as a result of this new tax law, which resulted in a non-cash tax benefit of $120.1 million for the year ended December 31, 2017. The 2017 Tax Act significantly changes how the U.S. taxes corporations for years after 2017, and requires complex computations to be performed that were not previously required under U.S. tax law. The provisions of the 2017 Tax Act will require significant judgments and estimates to be made, and management’s interpretations of these provisions could differ from those of the U.S. Treasury Department or the IRS, which has yet to promulgate most regulations implementing the 2017 Tax Act. As management completes its analysis of the 2017 Tax Act, adjustments to the provisional amounts that have been recorded may be required, which could materially affect the Company’s provision for income taxes in the period of adjustment. As of December 31, 2017, the Company has not made a provision for U.S. income taxes on unremitted foreign earnings because such earnings are considered to be insignificant. The Company and its subsidiaries file income tax returns in numerous tax jurisdictions, including U.S. federal, most U.S. states and certain foreign jurisdictions. Although management believes its calculations for tax returns are correct and the positions taken thereon are reasonable, the final outcome of income tax examinations could be materially different from the resolution management currently anticipates and the estimates that are reflected in the consolidated financial statements, which could materially affect the Company’s results of operations in a particular period. To the extent interest and penalties are assessed by taxing authorities, such amounts are accrued and included within income tax expense. Stock-Based Compensation The Company has certain stock-based compensation plans, under which restricted stock awards and restricted stock units (together “restricted shares”) are available for issuance to eligible employees and directors. Non-cash stock-based compensation expense is included within general and administrative expense in the consolidated statements of operations. Share-based payments, to the extent they are compensatory, are recognized based on their grant date fair values. Forfeitures are recorded as they occur. The Company records a deferred tax asset, or future tax benefit, based on the amount of share-based compensation recognized in the financial statements over the vesting period of share-based awards. The Company adopted ASU 2016-09, Compensation - Stock Compensation (Topic 718): Improvements to Employee Share-Based Payment Accounting (“ASU 2016-09”) effective January 1, 2017, which changed the accounting for excess tax benefits and deficiencies, which represent the tax effect of differences between the fair value of a share-based award on the date of vesting and the date of grant. Under ASU 2016-09, excess tax benefits or tax deficiencies are recognized in the income statement, rather than as additional paid-in-capital as under the previous guidance, and are presented as operating cash flows, rather than as a financing activity. Additionally, this ASU allowed companies to account for forfeitures of share-based payments as they occur, and increased the amount of tax that can be withheld by an employer for employee tax withholdings without resulting in liability classification of an award. Payments to taxing authorities for such employee withholdings are required to be presented as financing activities in the consolidated statements of cash flows. The provisions of ASU 2016-09 that were applicable to the Company were adopted on a prospective basis. The requirement to classify payments to taxing authorities for employee withholdings as a financing activity was consistent with the Company’s existing methodology, therefore did not result in a change. The adoption of ASU 2016-09 is expected to result in volatility in income tax expense given that excess tax benefits and deficiencies are recognized in income tax expense in the periods in which they occur. The other components of this ASU did not have a material effect on the consolidated financial statements. See Note 2 - Earnings Per Share, Note 9 - Stock-Based Compensation and Other Employee Benefit Plans and Note 12 - Income Taxes for additional information. Grants of restricted shares are valued based on the closing market share price of MasTec’s common stock as reported on the New York Stock Exchange (the “market price”) on the date of grant. Compensation expense arising from restricted shares is recognized on a straight line basis over the vesting period. Grants of restricted shares have cliff vesting terms, which generally vest over a period of 3 years. Upon vesting of share-based awards, some of the underlying shares are generally sold to cover the required withholding taxes. However, some participants may choose the net share settlement method to cover withholding tax requirements, in which case shares are not issued, but are treated as common stock repurchases in the consolidated financial statements, as they reduce the number of shares that would have been issued upon vesting. The Company then pays the corresponding withholding taxes to the appropriate taxing authorities in cash on behalf of the recipient. In addition, shares have either been sold or withheld to cover withholding tax requirements and/or to cover the exercise price for past option exercises. Withheld shares, which are valued at the market price on the date of vesting or exercise, as applicable, are recorded as a reduction to additional paid-in capital and are reflected as a financing activity within the consolidated statements of cash flows. Shares withheld for employee taxes and the exercise price of options totaled approximately 138,519, 44,988, and 74,407 for the years ended December 31, 2017, 2016 and 2015, respectively. Total payments for employee tax obligations to taxing authorities for withheld shares were $6.2 million, $0.6 million and $1.1 million for the years ended December 31, 2017, 2016 and 2015, respectively. The Company has certain employee stock purchase plans under which shares of the Company’s common stock are available for purchase by eligible employees. These plans allow qualified employees to purchase MasTec, Inc. common stock at 85% of its fair market value at the lower of (i) the date of commencement of the offering period or (ii) the last day of the exercise period, as defined in the plan documents. The fair value of purchases under the Company’s employee stock purchase plans is estimated using the Black-Scholes option-pricing valuation model. The determination of fair value of stock-based awards using an option-pricing model is affected by the Company’s stock price as well as assumptions pertaining to several variables, including expected stock price volatility, the expected term of the award and the risk-free rate of interest. In the option-pricing model for the Company’s employee stock purchase plans, expected stock price volatility is based on historical volatility of the Company’s common stock. The expected term of the award is based on historical and expected exercise patterns and the risk-free rate of interest is based on U.S. Treasury yields. The Company has not paid dividends in the past, and does not anticipate paying dividends in the foreseeable future, and therefore uses an expected dividend yield of zero. Collective Bargaining Agreements and Multiemployer Plans Certain of MasTec’s subsidiaries, including certain subsidiaries in Canada, are party to various collective bargaining agreements with unions representing certain of their employees. These agreements require the subsidiaries party to the agreements to pay specified wages, provide certain benefits to their union employees and contribute certain amounts to multiemployer pension and other multiemployer benefit plans and trusts (“MEPPs”). These contributions are recorded as a component of employee wages and salaries within costs of revenue, excluding depreciation and amortization. Contributions are generally based on fixed amounts per hour per employee for employees covered under these plans. Multiemployer plan contribution rates are determined annually and assessed on a “pay-as-you-go” basis based on union employee payrolls. The Pension Protection Act of 2006, as amended, (the “PPA”) requires pension plans that are underfunded to improve their funding ratios within prescribed intervals based on their level of underfunding, under which benefit reductions may apply and/or participating employers could be required to make additional contributions. In addition, if a multiemployer defined benefit plan fails to satisfy certain minimum funding requirements, the Internal Revenue Service (the “IRS”) may impose on the employers contributing to such plan a non-deductible excise tax of 5% of the amount of the accumulated funding deficiency. Union payrolls cannot be determined for future periods because the number of union employees employed at any given time, and the plans in which they may participate, vary depending upon the location and number of ongoing projects at a given time and the need for union resources in connection with those projects. The collective bargaining agreements expire at various times and have typically been renegotiated and renewed on terms similar to the ones contained in the expiring agreements. Under current law pertaining to employers that are contributors to U.S.-registered multiemployer defined benefit plans, a plan’s termination, an employer’s voluntary withdrawal from, or the mass withdrawal of contributing employers from, an underfunded multiemployer defined benefit plan requires participating employers to make payments to the plan for their proportionate share of the multiemployer plan’s unfunded vested liabilities. These liabilities include an allocable share of the unfunded vested benefits of the plan for all plan participants, not only for benefits payable to participants of the contributing employer. As a result, participating employers may bear a higher proportion of liability for unfunded vested benefits if the other participating employers cease to contribute to, or withdraw from, the plan. The allocable portion of liability to participating employers could be more disproportionate if employers that have withdrawn from the plan are insolvent, or if they otherwise fail to pay their proportionate share of the withdrawal liability. If the Company is subject to a withdrawal liability, the related withdrawal charge is recorded as a component of employee wages and salaries within costs of revenue, excluding depreciation and amortization, with any related liability recorded within other current and/or other long-term liabilities, as appropriate. The Company’s participation in the multiemployer pension plans is evaluated by management on an ongoing basis. See Note 10 - Other Retirement Plans and Note 14 - Commitments and Contingencies. Restructuring Activities From time to time, the Company may incur costs to streamline its business operations. These streamlining efforts, which are designed to improve profitability, could include eliminating service offerings that no longer fit into the Company’s business plan, certain integration activities for acquired businesses, reducing or eliminating services or operations that do not produce adequate revenue or margins, or reducing costs of business units that need margin improvements. The costs associated with these efforts, which we refer to as restructuring charges, include such items as employee separation costs, lease termination expenses and losses on disposal of excess fixed assets. When these efforts are related to circumstances that are significant, unique in nature and outside of the course of the Company’s normal and periodic business streamlining efforts, the related amount of restructuring charges included within the consolidated financial statements is aggregated and accompanied by a discussion of the nature of such restructuring activities. Restructuring charges are included within the applicable line item(s) in the consolidated statement of operations based on the nature of the expense incurred. For the year ended December 31, 2017, restructuring charges were not material. For the year ended December 31, 2016, restructuring charges related to significant streamlining actions for the Company’s electrical transmission and certain of the Company’s western Canadian oil and gas operations consisted primarily of $12.3 million of employee separation and other restructuring-type costs, including lease termination expenses, which were included within general and administrative expenses, and $2.9 million of losses on the disposal of excess fixed assets, which were included within other expense. Liabilities associated with these restructuring activities totaled $2.2 million and $5.7 million as of December 31, 2017 and 2016, respectively, and were included within various current liability accounts. Assets classified as held-for-sale totaled $1.1 million as of December 31, 2016 and were classified within other current assets. Litigation and Contingencies Accruals for litigation and contingencies are reflected in the consolidated financial statements based on management’s assessment, including advice of legal counsel, of the expected outcome of litigation or other dispute resolution proceedings and/or the expected resolution of contingencies. Liabilities for estimated losses are accrued if the potential loss from any claim or legal proceeding is considered probable and the amount can be reasonably estimated. Significant judgment is required in both the determination of probability of loss and the determination as to whether the amount is reasonably estimable. Accruals are based only on information available at the time of the assessment due to the uncertain nature of such matters. As additional information becomes available, management reassesses potential liabilities related to pending claims and litigation and may revise its previous estimates, which could materially affect the Company’s results of operations in a given period. New Accounting Pronouncements Accounting Pronouncements To Be Adopted in 2018 Revenue Recognition In May 2014, the Financial Accounting Standards Board (“FASB”) issued Accounting Standards Update (“ASU”) 2014-09, Revenue from Contracts with Customers (Topic 606) (“ASU 2014-09”). The core principle of this ASU is that a company will recognize revenue when it transfers goods or services to customers in an amount that reflects the consideration to which it expects to be entitled in exchange for those goods or services. In doing so, companies will need to use judgment and make estimates when evaluating contract terms and other relevant facts and circumstances. Additionally, ASU 2014-09 requires enhanced disclosures about the nature, amount, timing and uncertainty of revenue and cash flows arising from customer contracts. In August 2015, the FASB issued ASU 2015-14, Revenue from Contracts with Customers (Topic 606): Deferral of the Effective Date, which delayed the effective date of ASU 2014-09 by one year. In 2016 and 2017, the FASB issued several accounting standards updates to clarify certain topics within ASU 2014-09, and to update certain other topics within the Accounting Standards Codification (“ASC”) to conform with the new guidance in Topic 606. The Company adopted ASU 2014-09, and its related ASUs, under the modified retrospective transition approach as of January 1, 2018, which applies to all new contracts initiated on or after January 1, 2018. For existing contracts that have not been substantially completed as of January 1, 2018, any difference between the recognition criteria in these ASUs and the Company’s current revenue recognition practices will be recognized using a cumulative effect adjustment to the opening balance of retained earnings as of January 1, 2018. The Company’s assessment of the effects of Topic 606 on its consolidated financial statements, financial statement disclosures, business processes, systems and controls included a detailed review of representative contracts at each of the Company’s business units and a comparison of its historical accounting policies and practices to Topic 606 as well as the information necessary to enable the preparation of the financial statements and related disclosures under the new standard, including its information technology capabilities and systems. Based on the Company’s review of its revenue arrangements, the Company expects to recognize revenue and earnings over time utilizing the cost-to-cost measure of progress for its fixed price contracts and certain master service and other service agreements, consistent with current practice. For these contracts, the cost-to-cost measure of progress best depicts the transfer of control of goods or services to the customer under Topic 606. Contracts recognized over time are typically comprised of a single performance obligation as the promise to transfer the individual goods or services is not distinct from other promises in the contract due to the significant integration services provided by the Company in connection with its contracts. For certain contracts governed by a master service or other service agreement, revenue will be recognized at the point in time when control has been transferred to the customer, which is generally when the work order has been fulfilled, as control is not continuously transferred to the customer as the services are provided. Contract modifications are routine in the performance of the Company’s contracts and are typically evidenced by a change order. In most instances, change orders relate to adjustments to prices and the scope of services provided, which are not distinct from the scope of services in the original contract. Therefore, change orders will typically be accounted for on a cumulative catch-up basis under Topic 606, consistent with the Company’s current practice. The Company’s future disclosures related to revenue recognition will include information about unsatisfied performance obligations and expectations of the timing of recognition for those obligations. The disclosure pertaining to unsatisfied performance obligations will be in addition to the Company’s existing unaudited backlog disclosure, which represents the amount of revenue the Company expects to recognize over the next 18 months. The future disclosure pertaining to unsatisfied performance obligations will include the full amount of any unsatisfied performance obligations, as compared with only the amount expected to be recognized over the next 18 months, and it will exclude estimates of future revenue under master service and other service agreements. Additionally, in the future, the Company’s disclosures will reflect the amount of contract assets and contract liabilities, as calculated on a by-contract basis. Based on the Company’s evaluation of its systems and information technology capabilities, the Company does not expect to incur significant information technology costs to modify its systems to be able to achieve the preparation and disclosure requirements of the new standard, however, has implemented targeted changes to its internal reporting processes to facilitate gathering the data needed for the reporting and disclosure requirements. The Company also implemented a training program for its business units related to implementation of Topic 606 and continues to develop the required disclosures. The Company has also implemented updates to its control processes and procedures based on changes resulting from Topic 606. The adoption of Topic 606 is not expected to have a material effect on the timing or amount of revenue recognized as compared to current practices, or to have a material effect on the Company’s internal controls over financial reporting. Based on review of existing contracts that have not been substantially completed as of January 1, 2018, the Company has estimated that the cumulative adjustment to beginning retained earnings resulting from the adoption of Topic 606 will not be material. Other Accounting Pronouncements To Be Adopted in 2018 In January 2017, the FASB issued ASU 2017-04, Intangibles - Goodwill and Other (Topic 350): Simplifying the Test for Goodwill Impairment (“ASU 2017-04”). ASU 2017-04 eliminates the second step in goodwill impairment testing, which requires that goodwill impairment losses be measured as the difference between the implied value of a reporting unit’s goodwill and its carrying amount. ASU 2017-04, which the Company early adopted as of January 1, 2018, is expected to reduce the cost and complexity of impairment testing by requiring goodwill impairment losses to be measured as the excess of the reporting unit’s carrying amount, including goodwill and related goodwill tax effects, over its fair value. Beginning in 2018, if the carrying value of a reporting unit’s goodwill exceeds its implied value, the resulting amount of goodwill impairment recorded in the Company’s consolidated financial statements could differ from the amount of goodwill impairment that would have been recorded prior to adoption of this ASU. Additionally, the FASB issued ASU 2017-01, Business Combinations (Topic 805): Clarifying the Definition of a Business (“ASU 2017-01”) in January 2017. ASU 2017-01 changes the definition of a business for purposes of evaluating whether a transaction represents an acquisition (or disposal) of assets or a business. The revised definition of a business under ASU 2017-01 will reduce the number of transactions that are accounted for as business combinations. ASU 2017-01, which the Company adopted as of January 1, 2018, is not expected to have a material effect on the consolidated financial statements. In May 2017, FASB issued ASU 2017-09, Compensation - Stock Compensation (Topic 718): Scope of Modification Accounting (“ASU 2017-09”). ASU 2017-09 clarifies when a change to the terms or conditions of a share-based payment award must be accounted for as a modification. Limited and administrative modifications that do not change the value, vesting conditions, or classification of the award are exempt from following the modification guidance in Topic 718. This ASU, which the Company adopted as of January 1, 2018, is not expected to have a material effect on the consolidated financial statements. In October 2016, the FASB issued ASU 2016-16, Income Taxes (Topic 740): Intra-Entity Transfers of Assets Other Than Inventory (“ASU 2016-16”), which eliminates the existing exception in U.S. GAAP prohibiting the recognition of the income tax consequences for intra-entity asset transfers. Under ASU 2016-16, entities will be required to recognize the income tax consequences of intra-entity asset transfers, other than for inventory, when the transfer occurs. ASU 2016-16, which the Company adopted as of January 1, 2018, will not have a material effect on the Company’s consolidated financial statements. In August 2016, the FASB issued ASU 2016-15, Statement of Cash Flows (Topic 230): Classification of Certain Cash Receipts and Cash Payments (“ASU 2016-15”) to reduce diversity in practice by providing guidance on the classification of certain cash receipts and payments in the statement of cash flows. This ASU, which the Company adopted as of January 1, 2018, is effective on a retrospective basis, and will result in the reclassification of certain types of activity in the consolidated statement of cash flows, as applicable to the prior year periods, beginning in 2018. For the year ended December 31, 2017, acquisition-related contingent consideration payments in excess of acquisition date liabilities totaling approximately $12 million will be reclassified from financing to operating cash flows. Proceeds from the settlement of insurance claims related to damaged property and equipment, which are required to be reclassified from operating to investing cash flows, were not material for the years ended December 31, 2017, 2016 or 2015. The other provisions of this ASU are not expected to have a material effect on the Company’s consolidated financial statements. In January 2016, the FASB issued ASU 2016-01, Financial Instruments - Overall (Subtopic 825-10): Recognition and Measurement of Financial Assets and Financial Liabilities (“ASU 2016-01”), which provides guidance for the recognition, measurement, presentation and disclosure of financial assets and financial liabilities. ASU 2016-01 requires equity investments with readily determinable fair values, except for those accounted for under the equity method of accounting or those that are consolidated, to be measured at fair value with changes in fair value recognized in net income. Equity investments that do not have readily determinable fair values are permitted to be remeasured upon the occurrence of an observable price change or upon identification of an impairment. ASU 2016-01 also requires enhanced disclosures for such investments and modifies certain other disclosure requirements. This ASU, which the Company adopted as of January 1, 2018, is effective on a modified retrospective basis, with exception for the amendments related to equity investments without readily determinable fair values, which is effective prospectively. The adoption of ASU 2016-01 may result in volatility in other income (expense), net, as a result of the remeasurement requirements for equity investments; however, the Company does not expect such changes to be material. The other components of this ASU are not expected to have a material effect on the Company’s consolidated financial statements. Other Recent Accounting Pronouncements In February 2018, the FASB issued ASU 2018-02, Income Statement - Reporting Comprehensive Income (Topic 220): Reclassification of Certain Tax Effects from Accumulated Other Comprehensive Income (“ASU 2018-02”). ASU 2018-02 permits entities to reclassify the tax effects related to the change in the federal tax rate as a result of the 2017 Tax Act from accumulated other comprehensive income to retained earnings. The guidance may be applied retrospectively or in the period of adoption. ASU 2018-02 is effective for fiscal years, and for interim periods within those fiscal years, beginning after December 15, 2018, with early adoption permitted. The Company is currently evaluating the effect of this ASU on its consolidated financial statements. In August 2017, the FASB issued ASU 2017-12, Derivatives and Hedging (Topic 815): Targeted Improvements to Accounting for Hedging Activities (“ASU 2017-12”). ASU 2017-12 amends the hedge accounting model in Topic 815 to enable entities to better portray the economics of their risk management activities in the financial statements and enhance the transparency and understandability of hedge results. The guidance eliminates the requirement to separately measure and report hedge ineffectiveness and generally requires the entire change in the fair value of a hedging instrument to be presented in the same income statement line as the hedged item. The guidance also simplifies certain documentation and assessment requirements. ASU 2017-12 is effective for fiscal years, and for interim periods within those fiscal years, beginning after December 15, 2018, with early adoption permitted. All transition requirements and elections should be applied to hedging relationships existing on the date of adoption and their effects should be reflected as of the beginning of the fiscal year of adoption. The presentation and disclosure requirements are effective on a prospective basis. The Company is currently evaluating the potential effect of this ASU on its consolidated financial statements. In February 2016, the FASB issued ASU 2016-02, Leases (Subtopic 842) (“ASU 2016-02”). ASU 2016-02 provides revised guidance for lease accounting and related disclosure requirements, including a requirement for lessees to recognize lease assets and lease liabilities for certain operating leases. Under the previous guidance, lessees were not required to recognize assets and liabilities for operating leases on the balance sheet. ASU 2016-02 is effective for fiscal years, and for interim periods within those fiscal years, beginning after December 15, 2018, with early adoption permitted. Modified retrospective application is required for all relevant prior periods. The Company is currently evaluating the potential effect of this ASU on its consolidated financial statements, including the potential amount of incremental lease assets and liabilities that are expected to be recognized upon adoption.

Earnings Per Share

12 Months Ended

Dec. 31, 2017

Earnings Per Share [Abstract]

Earnings Per Share

Note 2 – Earnings Per Share

Basic earnings or loss per share is computed by dividing net income or loss attributable to MasTec by the weighted average number of common shares outstanding for the period, which excludes non-participating unvested restricted share awards. Diluted earnings per share is computed by dividing net income or loss attributable to MasTec by the weighted average number of fully diluted shares, as calculated under the treasury stock method, which includes the potential effect of dilutive common stock equivalents, such as issued but unvested restricted shares. If the Company reports a loss, rather than income, the computation of diluted loss per share excludes the effect of dilutive common stock equivalents, as their effect would be anti-dilutive.

As discussed in Note 1 - Business, Basis of Presentation and Significant Accounting Policies, the Company adopted ASU 2016-09 effective January 1, 2017 on a prospective basis. ASU 2016-09 changed the recognition of excess tax benefits or tax deficiencies upon the vesting of share-based payment awards from additional paid-in capital, within equity, to income tax benefit or expense, within the statement of operations. As a result, excess tax benefits or deficiencies under ASU 2016-09 are excluded from assumed proceeds under the treasury stock method, whereas under previous guidance, such amounts were included within assumed proceeds. For the year ended December 31, 2017, this resulted in the inclusion of approximately 0.3 million incremental shares in the Company’s total weighted average diluted shares outstanding.

The following table provides details underlying the Company’s earnings per share calculations for the periods indicated (in thousands):



	For the Years Ended December 31,
	2017		2016		2015
Net income (loss) attributable to MasTec:
Net income (loss) - basic and diluted^(a)	$	347,213	$	131,263	$	(79,110	)
Weighted average shares outstanding:
Weighted average shares outstanding - basic	80,903		80,372		80,489
Dilutive common stock equivalents	1,422		1,022		—
Weighted average shares outstanding - diluted	82,325		81,394		80,489

Additional information:
Weighted average anti-dilutive common stock equivalents ^(b)	—		31		564


(a)	Calculated as total net income (loss) less amounts attributable to non-controlling interests.


(b)	For the year ended December 31, 2016, represents anti-dilutive common stock equivalents as calculated under the treasury stock method, and, for the year ended December 31, 2015, represents anti-dilutive common stock equivalents due to the Company having reported a net loss.

Goodwill and Other Intangible Assets

12 Months Ended

Dec. 31, 2017

Goodwill and Intangible Assets Disclosure [Abstract]

Goodwill and Other Intangible Assets

Note 3 - Goodwill and Other Intangible Assets

The following table provides a reconciliation of changes in goodwill by reportable segment for the periods indicated (in millions):



	Communications		Oil and Gas			Electrical Transmission		Power Generation and Industrial		Total Goodwill
Goodwill, gross, as of December 31, 2015	$	414.9	$	374.6		$	149.9	$	117.6	$	1,057.0
Accumulated impairment loss ^(a)	—		(68.5		)	—		—		(68.5		)
Goodwill, net, as of December 31, 2015	$	414.9	$	306.1		$	149.9	$	117.6	$	988.5
Accruals of acquisition-related contingent consideration, net^(b)	5.8		—			—		—		5.8
Currency translation adjustments	—		1.6			—		—		1.6
Goodwill, net, as of December 31, 2016	$	420.7	$	307.7		$	149.9	$	117.6	$	995.9
Additions from new business combinations	45.7		74.1			—		18.2		138.0
Currency translation adjustments	—		3.8			—		—		3.8
Goodwill, net, as of December 31, 2017	$	466.4	$	385.6		$	149.9	$	135.8	$	1,137.7
Accumulated impairment loss ^(a)	—		(74.8		)	—		—		(74.8		)
Goodwill, gross, as of December 31, 2017	$	466.4	$	460.4		$	149.9	$	135.8	$	1,212.5


(a)	Accumulated impairment losses include the effect of currency translation gains and/or losses.


(b)	Represents contingent consideration for acquisitions prior to January 1, 2009, which is accrued as incurred, in accordance with U.S. GAAP.

The following table provides a reconciliation of changes in other intangible assets for the periods indicated (in millions):



	Other Intangible Assets
	Non-amortizing					Amortizing
	Trade Names			Pre-Qualifications		Customer Relationships and Backlog			Other ^(a)			Total
Other intangible assets, gross, as of December 31, 2015	$	34.8		$	73.4	$	195.4		$	25.7		$	329.3
Accumulated amortization						(114.6		)	(15.3		)	(129.9		)
Other intangible assets, net, as of December 31, 2015	$	34.8		$	73.4	$	80.8		$	10.4		$	199.4
Amortization expense						(17.9		)	(3.4		)	(21.3		)
Currency translation adjustments	—			1.2		0.3			0.1			1.6
Other activity	(0.3		)	—		—			0.3			—
Other intangible assets, net, as of December 31, 2016	$	34.5		$	74.6	$	63.2		$	7.4		$	179.7
Additions from new business combinations	—			—		26.3			2.5			28.8
Amortization expense						(19.3		)	(1.6		)	(20.9		)
Currency translation adjustments	—			3.0		0.4			0.1			3.5
Other intangible assets, net, as of December 31, 2017	$	34.5		$	77.6	$	70.6		$	8.4		$	191.1
Remaining weighted average amortization period (in years)						9			8			9


(a)	Consists principally of trade names and non-compete agreements.

Amortization expense associated with intangible assets for the years ended December 31, 2017, 2016 and 2015 totaled $20.9 million, $21.3 million and $28.4 million, respectively. Expected future amortization expense as of December 31, 2017 is summarized in the following table (in millions):



	Amortization Expense
2018	$	19.5
2019	13.4
2020	11.0
2021	8.4
2022	6.9
Thereafter	19.8
Total	$	79.0

2017 Acquisitions. During the year ended December 31, 2017, MasTec completed three acquisitions, which included all of the equity interests in: (i) a wireline/fiber deployment construction contractor, which is included in the Company’s Communications segment; (ii) a heavy civil construction services company, which is included in the Company’s Power Generation and Industrial segment, and (iii) an oil and gas pipeline equipment company, which is included in the Company’s Oil and Gas segment. Determination of the estimated fair values of the net assets acquired and the estimated earn-out liabilities for these acquisitions is preliminary as of December 31, 2017, and further adjustments to these estimates may occur.

The following table summarizes the estimated fair values of consideration paid and net assets acquired as of the respective dates of acquisition, as adjusted (in millions):



Acquisition consideration:	2017
Cash	$	117.9
Fair value of contingent consideration (earn-out liability)	93.5
Total consideration transferred	$	211.4
Identifiable assets acquired and liabilities assumed:
Current assets, primarily composed of accounts receivable and $2.8 million of cash acquired	$	42.7
Property and equipment	56.7
Amortizing intangible assets	28.8
Other long-term assets	0.5
Current liabilities, including current portion of capital lease obligations and long-term debt	(29.2		)
Long-term debt, including capital lease obligations	(9.9		)
Deferred income taxes	(16.2		)
Total identifiable net assets	$	73.4
Goodwill	$	138.0
Total net assets acquired, including goodwill	$	211.4

Amortizing intangible assets related to the 2017 acquisitions are primarily composed of customer relationships, backlog and other amortizing intangible assets, which had weighted average lives of approximately 11 years, 4 years and 7 years, respectively, and a weighted average life of 10 years in total, and will be amortized in a manner consistent with the pattern in which the related benefits are expected to be consumed. The goodwill balances for the respective acquisitions represent the estimated value of each acquired company’s geographic presence in key markets, its assembled workforce and management team industry-specific project management expertise, as well as synergies expected to be achieved from the combined operations of the acquired companies and MasTec. Approximately $75 million of the acquired goodwill balance as of December 31, 2017 is expected to be tax deductible.

The contingent consideration included in the table above equals the acquired companies’ earnings before interest, taxes, depreciation and amortization (“EBITDA”) above certain thresholds, if applicable, for a period of five years, as set forth in the respective purchase agreements, which amounts are payable annually. The fair values of the earn-out liabilities were estimated using income approaches such as discounted cash flows or option pricing models and incorporate significant inputs not observable in the market. Key assumptions in the estimated valuations include the discount rate and probability-weighted EBITDA projections. Significant changes in any of these assumptions could result in a significantly higher or lower potential earn-out liability. As of December 31, 2017, the range of potential undiscounted earn-out liabilities for the 2017 acquisitions was estimated to be between $9 million and $185 million; however, there is no maximum payment amount.

For the years ended December 31, 2017 and 2016, unaudited pro forma revenue totaled approximately $6,680.2 million and $5,320.1 million, respectively, and unaudited pro forma net income totaled approximately $354.9 million and $140.0 million, respectively.

The above indicated unaudited pro forma financial results, which represent the results of operations of the companies acquired as if the acquired companies had been consolidated as of January 1, 2016, are provided for illustrative purposes only and do not purport to be indicative of the actual results that would have been achieved by the combined companies for the periods indicated, or of the results that may be achieved by the combined companies in the future. The unaudited supplemental pro forma financial results have been prepared by adjusting the historical results of MasTec to include the historical results of the acquired businesses described above, and then adjusted (i) to remove acquisition costs; (ii) to increase amortization expense resulting from the acquired intangible assets; (iii) to increase interest expense as a result of the cash consideration paid; (iv) to reduce interest expense from debt repaid upon acquisition; and (iv) to eliminate the effects of intercompany transactions. These unaudited supplemental pro forma financial results do not include adjustments to reflect other cost savings or synergies that may have resulted from these acquisitions. Future results may vary significantly due to future events and transactions, as well as other factors, many of which are beyond MasTec’s control.

For the years ended December 31, 2017, acquisition-related results included in the Company’s consolidated results of operations included revenue of approximately $160.1 million and net income of approximately $10.2 million, based on the consolidated effective tax rate including the effect of the 2017 Tax Act. These acquisition-related results do not include the effects of acquisition costs or interest expense associated with consideration paid for the related acquisitions.

Fair Value of Financial Instruments

The entire disclosure for the aggregate amount of goodwill and a description of intangible assets, which may include (a) for amortizable intangible assets (also referred to as finite-lived intangible assets), the carrying amount, the amount of any significant residual value, and the weighted-average amortization period, (b) for intangible assets not subject to amortization (also referred to as indefinite-lived intangible assets), the carrying amount, and (c) the amount of research and development assets acquired and written off in the period, including the line item in the income statement in which the amounts written off are aggregated, if not readily apparent from the income statement. Also discloses (a) for amortizable intangibles assets in total and by major class, the gross carrying amount and accumulated amortization, the total amortization expense for the period, and the estimated aggregate amortization expense for each of the five succeeding fiscal years, (b) for intangible assets not subject to amortization the carrying amount in total and by major class, and (c) for goodwill, in total and for each reportable segment, the changes in the carrying amount of goodwill during the period (including the aggregate amount of goodwill acquired, the aggregate amount of impairment losses recognized, and the amount of goodwill included in the gain (loss) on disposal of a reporting unit). If any part of goodwill has not been allocated to a reportable segment, discloses the unallocated amount and the reasons for not allocating. For each impairment loss recognized related to an intangible asset (excluding goodwill), discloses: (a) a description of the impaired intangible asset and the facts and circumstances leading to the impairment, (b) the amount of the impairment loss and the method for determining fair value, (c) the caption in the income statement or the statement of activities in which the impairment loss is aggregated, and (d) the segment in which the impaired intangible asset is reported. For each goodwill impairment loss recognized, discloses: (a) a description of the facts and circumstances leading to the impairment, (b) the amount of the impairment loss and the method of determining the fair value of the associated reporting unit, and (c) if a recognized impairment loss is an estimate not finalized and the reasons why the estimate is not final. May also disclose the nature and amount of any significant adjustments made to a previous estimate of an impairment loss.

+ References + Details

Fair Value of Financial Instruments

12 Months Ended

Dec. 31, 2017

Fair Value Disclosures [Abstract]

Note 4 - Fair Value of Financial Instruments

Assets and Liabilities Measured at Fair Value on a Recurring Basis

As of December 31, 2017 and 2016, financial instruments required to be measured at fair value on a recurring basis consisted primarily of acquisition-related contingent consideration, or “earn-out” liabilities, which represents the estimated fair value of future amounts payable for acquisitions of businesses and other interests. Acquisition-related contingent consideration liabilities are based on management estimates and entity-specific assumptions, which are Level 3 inputs, and are evaluated on an ongoing basis. As of December 31, 2017 and 2016, the estimated fair value of the Company’s earn-out liabilities totaled $117.2 million and $45.8 million, respectively, of which $22.6 million and $21.8 million, respectively, was included within other current liabilities. The fair value of the Company’s earn-out liabilities is estimated using income approaches such as discounted cash flows or option pricing models and incorporates significant inputs not observable in the market. Key assumptions include the discount rate and probability-weighted EBITDA projections. Significant changes in any of these assumptions could result in a significantly higher or lower potential earn-out liability. As of December 31, 2017, the range of potential undiscounted earn-out liabilities was estimated to be between $22.0 million and $204.8 million; however, there is no maximum payment amount.

Acquisition-related contingent consideration activity consists primarily of: additions from new business combinations and acquisitions of other interests; payments of acquisition-related contingent consideration; changes in the expected fair value of future earn-out obligations; and, for earn-out liabilities denominated in foreign currencies, translation gains or losses. Fair value adjustments for earn-out liabilities are recorded within other income or expense, as appropriate, and foreign currency translation activity is recorded within other comprehensive income or loss, as appropriate.

For the year ended December 31, 2017, additions from acquisitions of businesses and other interests totaled $102.5 million. Acquisition-related contingent consideration payments totaled approximately $18.8 million, $15.8 million and $40.5 million for the years ended December 31, 2017, 2016 and 2015, respectively. For the years ended December 31, 2017 and 2016, foreign currency translation activity was de minimis, and foreign currency translation gains totaled $8.0 million for the year ended December 31, 2015. In 2017, the Company recognized a reduction in the estimated fair value of future earn-out obligations of $12.3 million for certain acquired businesses in the Communications and Electrical Transmission segments. In 2016, the Company recognized a net increase in the estimated fair value of future earn-out obligations of $2.7 million for certain acquired businesses in the Oil and Gas segment, partially offset by a reduction for certain other acquired businesses in the Oil and Gas and Communications segments upon finalization of the related earn-out arrangements. In 2015, the Company recognized a net reduction of $39.2 million for earn-out obligations in the Oil and Gas, Electrical Transmission and Communications segments, of which $20.1 million related to finalization of earn-out arrangements and adjustments to the expected future earn-out obligations of certain acquired businesses, and of which $19.1 million was offset with a corresponding receivable amount.

Assets and Liabilities Measured at Fair Value on a Non-Recurring Basis

Assets and liabilities recognized or disclosed at fair value on a non-recurring basis, for which remeasurement occurs in the event of an impairment or other measurement event, if applicable, include items such as equity investments, life insurance assets, long-lived assets, goodwill, other intangible assets and debt.

As of both December 31, 2017 and 2016, the gross carrying amount of the Company’s 4.875% Senior Notes totaled $400 million. As of December 31, 2017 and 2016, the estimated fair value of the 4.875% Senior Notes, based on quoted market prices in active markets, a Level 1 input, totaled $410.0 million and $388.0 million, respectively.

Cost and Equity Investees. The Company’s cost and equity investees as of December 31, 2017 include: (i) the Company’s 33% equity interests in Trans-Pecos Pipeline, LLC (“TPP”) and Comanche Trail Pipeline, LLC (“CTP,” and together with TPP, the “Waha JVs”); (ii) a $15 million cost investment in Cross Country Infrastructure Services, Inc. (“CCI,” previously, Cross Country Pipeline Supply, Inc.); (iii) the Company’s interests in its proportionately consolidated non-controlled contractual joint ventures; (iv) the Company’s equity interests in Pensare Acquisition Corp. (“Pensare”); and (v) certain other cost and equity method investments. See below and Note 15 - Related Party Transactions.

The fair values of the Company’s cost and equity method investments are not readily observable. Equity investments are reviewed for impairment by assessing whether there has been a decline in the fair value of the investment below the carrying value, and whether that decline is considered to be other than temporary. In making this determination, factors such as the ability to recover the carrying amount of the investment and the inability of the investee to sustain future earnings capacity are considered. The Company is not aware of events or changes in circumstances that would have a significant adverse effect on the carrying values of its cost or equity method investments as of December 31, 2017 or 2016. Cumulative undistributed earnings from the Company’s significant equity method investees totaled $16.9 million as of December 31, 2017.

The Waha JVs. The Waha JVs own and operate two pipelines and a header system that transport natural gas to the Mexican border for export. These pipelines, which interconnect with pipelines in Mexico, commenced operations in 2017. For the years ended December 31, 2017 and 2016, the Company made equity and other contributions to these joint ventures of approximately $73 million and $27 million, respectively, and for the year ended December 31, 2015, the Company made no net contributions. As collateral for its equity commitments in the Waha JVs, the Company has issued letters of credit (the “Equity LC Amount”), of which $19 million and $91 million, respectively, were outstanding as of December 31, 2017 and 2016.

Equity in earnings related to the Company’s proportionate share of income from the Waha JVs, which is included within the Company’s Other segment, totaled approximately $21.3 million for the year ended December 31, 2017, and for the year ended December 31, 2016, was de minimis. For the year ended December 31, 2015, the Company’s proportionate share of losses totaled $4.4 million and related to the Waha JVs interest rate swaps. The Company’s net investment in the Waha JVs totaled approximately $121 million and $6 million as of December 31, 2017 and 2016, respectively. The Company’s net investment in the Waha JVs differs from its proportionate share of the net assets of the Waha JVs due to capitalized investment costs as well as the effect of intercompany eliminations. Beginning in 2016, certain subsidiaries of MasTec provided pipeline construction services to the Waha JVs. For the years ended December 31, 2017 and 2016, revenue recognized in connection with work performed for the Waha JVs, including intercompany eliminations, totaled $256.1 million and $245.0 million, respectively. Related receivables, including retainage, net of BIEC, totaled $2.8 million and $71.2 million as of December 31, 2017 and 2016, respectively.

TPP and CTP are party to separate non-recourse financing facilities, which are each secured by pledges of the equity interests in the respective entities, as well as a first lien security interest over virtually all of TPP’s and CTP’s assets. The Waha JVs are also party to certain interest rate swaps, which, beginning in 2016, have been accounted for as qualifying cash flow hedges. The Company reflects its proportionate share of any unrealized fair market value gains or losses from fluctuations in interest rates associated with these swaps within other comprehensive income or loss, as appropriate. For the years ended December 31, 2017 and 2016, the Company’s proportionate share of unrecognized unrealized activity on these interest rate swaps were gains of approximately $0.8 million and $6.4 million, respectively, or $0.5 million and $4.0 million, respectively, net of tax. For the year ended December 31, 2015, the Company’s proportionate share of unrealized losses from these swaps totaling $4.4 million was included within equity in (earnings) losses of unconsolidated affiliates.

Other investments. During the third quarter of 2017, the Company paid $2.0 million for approximately 4% of the common stock of Pensare and warrants to purchase 2.0 million shares of Pensare common stock, which is a special purpose acquisition company focusing on transactions in the telecommunications industry. The shares of common stock purchased by MasTec are not transferable or salable until one year after Pensare successfully completes a business combination transaction, with limited exceptions, as specified in the agreement. The warrants purchased by MasTec are exercisable at a purchase price of $11.50 per share after Pensare successfully completes a business combination. Both the warrants and shares expire and/or are effectively forfeitable if Pensare does not successfully complete a business combination by February 1, 2019. The warrants, which are derivative financial instruments, and the shares, which are a cost method investment, are included within other long-term assets in the Company’s consolidated financial statements as of December 31, 2017. The fair value of the warrants, as determined based on Level 3 inputs, approximated their cost basis as of December 31, 2017. The fair value of the shares is not readily determinable due to the nature of the restrictions. José R. Mas, MasTec’s Chief Executive Officer, is a director of Pensare.

In connection with the 2014 acquisition of Pacer Construction Holdings Corporation and its affiliated operating companies (collectively, “Pacer”), the Company acquired equity interests in two joint ventures. As of March 2016, all related project work had been completed. One of these entities was liquidated in 2016, and the second, which is in the final stages of liquidation, is being managed by a receiver to assist with the orderly wind-down of its operations. The Company received $22.5 million of proceeds from the receiver in 2017. The remaining investment, for which the Company has minimal involvement, is reviewed regularly by corporate management for potential changes in expected recovery estimates. For the years ended December 31, 2017 and 2016, the Company recorded $0.4 million of expense and $3.6 million of income, respectively, related to changes in expected recovery amounts. The net carrying value, which is included within other current assets, totaled $9.6 million and $31.4 million as of December 31, 2017 and 2016, respectively. In 2016 and 2015, Pacer performed construction services on behalf of these entities and recognized revenue totaling $0.6 million and $2.9 million, respectively, for the years ended December 31, 2016 and 2015.

Summarized Financial Information of Equity Method Investments

The following presents summarized information for the Company’s significant equity method investments (in millions):



	December 31,
	2017		2016
Current assets	$	136.8	$	89.5
Long-term assets	1,306.3		1,126.5
Total assets	$	1,443.1	$	1,216.0

Current liabilities	$	121.2	$	153.6
Long-term liabilities	976.5		986.0
Total liabilities	$	1,097.7	$	1,139.6



	For the Years Ended December 31,
	2017		2016			2015
Revenue	$	114.5	$	—		$	—
Net income (loss)	$	64.5	$	(0.2	)	$	(13.3	)

Accounts Receivable, Net of Allowance

The entire disclosure for the fair value of financial instruments (as defined), including financial assets and financial liabilities (collectively, as defined), and the measurements of those instruments as well as disclosures related to the fair value of non-financial assets and liabilities. Such disclosures about the financial instruments, assets, and liabilities would include: (1) the fair value of the required items together with their carrying amounts (as appropriate); (2) for items for which it is not practicable to estimate fair value, disclosure would include: (a) information pertinent to estimating fair value (including, carrying amount, effective interest rate, and maturity, and (b) the reasons why it is not practicable to estimate fair value; (3) significant concentrations of credit risk including: (a) information about the activity, region, or economic characteristics identifying a concentration, (b) the maximum amount of loss the entity is exposed to based on the gross fair value of the related item, (c) policy for requiring collateral or other security and information as to accessing such collateral or security, and (d) the nature and brief description of such collateral or security; (4) quantitative information about market risks and how such risks are managed; (5) for items measured on both a recurring and nonrecurring basis information regarding the inputs used to develop the fair value measurement; and (6) for items presented in the financial statement for which fair value measurement is elected: (a) information necessary to understand the reasons for the election, (b) discussion of the effect of fair value changes on earnings, (c) a description of [similar groups] items for which the election is made and the relation thereof to the balance sheet, the aggregate carrying value of items included in the balance sheet that are not eligible for the election; (7) all other required (as defined) and desired information.

+ References + Details

Accounts Receivable, Net of Allowance

12 Months Ended

Dec. 31, 2017

Receivables [Abstract]

Note 5 - Accounts Receivable, Net of Allowance

The following table provides details of accounts receivable, net of allowance, as of the dates indicated (in millions):



	December 31,
	2017			2016
Contract billings	$	683.9		$	564.2
Retainage	323.1			268.6
Costs and earnings in excess of billings	599.2			331.6
Accounts receivable, gross	$	1,606.2		$	1,164.4
Less allowance for doubtful accounts	(8.2		)	(8.4		)
Accounts receivable, net	$	1,598.0		$	1,156.0

Retainage, which has been billed, but is not due until completion of performance and acceptance by customers, is expected to be collected within one year. Receivables expected to be collected beyond one year are recorded within other long-term assets.

Activity in the allowance for doubtful accounts for the periods indicated is as follows (in millions):



	For the Years Ended December 31,
	2017			2016
Allowance for doubtful accounts at beginning of year	$	8.4		$	7.7
Provision for doubtful accounts	2.6			2.9
Amounts charged against the allowance	(2.8		)	(2.2		)
Allowance for doubtful accounts at end of year	$	8.2		$	8.4

The Company is party to non-recourse financing arrangements in the ordinary course of business, under which certain receivables are settled with the customer’s bank in return for a nominal fee. These arrangements, under which amounts can vary based on levels of activity and changes in customer payment terms, improve the collection cycle time of the related receivables. Cash collected from this arrangement is reflected within cash provided by operating activities in the consolidated statements of cash flows. The discount charge, which is included within interest expense, net, totaled approximately $6.0 million, $2.7 million and $1.6 million for the years ended December 31, 2017, 2016 and 2015, respectively.

Property, Plant and Equipment [Abstract]

The entire disclosure for claims held for amounts due a entity, excluding financing receivables. Examples include, but are not limited to, trade accounts receivables, notes receivables, loans receivables. Includes disclosure for allowance for credit losses.

+ References + Details

Property and Equipment, Net

12 Months Ended

Dec. 31, 2017

Property and Equipment, Net

Note 6 - Property and Equipment, Net

The following table provides details of property and equipment, net, including property and equipment held under capital leases as of the dates indicated (in millions):



	December 31,
	2017			2016			Estimated Useful Lives (in years)
Land	$	4.6		$	4.6
Buildings and leasehold improvements	26.7			24.2			3-40
Machinery and equipment	1,261.9			997.8			2-20
Office furniture and equipment	149.9			146.1			3-7
Construction in progress	12.5			9.5
Total property and equipment	$	1,455.6		$	1,182.2
Less accumulated depreciation and amortization	(749.1		)	(633.1		)
Property and equipment, net	$	706.5		$	549.1

The gross amount of capitalized internal-use software, which is included within office furniture and equipment, totaled $109.9 million and $107.8 million as of December 31, 2017 and 2016, respectively. Capitalized internal-use software, net of accumulated amortization, totaled $23.5 million and $30.9 million as of December 31, 2017 and 2016, respectively. Depreciation and amortization expense associated with property and equipment for the years ended December 31, 2017, 2016 and 2015 totaled $167.2 million, $143.6 million and $141.3 million, respectively.

Debt

12 Months Ended

Dec. 31, 2017

Debt Disclosure [Abstract]

Debt

Note 7 - Debt

The following table provides details of the carrying values of debt as of the dates indicated (in millions):



		December 31,
Description	Maturity Date	2017			2016
Senior secured credit facility:	February 22, 2022
Revolving loans		$	377.7		$	279.9
Term loan		396.9			237.5
4.875% Senior Notes	March 15, 2023	400.0			400.0
Capital lease obligations, weighted average interest rate of 3.5%	In installments through September 1, 2022	181.2			98.6
Other debt obligations	Varies	25.8			19.8
Total long-term debt obligations		$	1,381.6		$	1,035.8
Less unamortized deferred financing costs		(13.0		)	(9.8		)
Total debt, net of deferred financing costs		$	1,368.6		$	1,026.0
Current portion of long-term debt		87.9			64.6
Long-term debt		$	1,280.7		$	961.4

Senior Secured Credit Facility

The Company has a senior secured credit facility (the “Credit Facility”), which was last amended and restated in February 2017. The Company refers to its amended and restated credit facility as the “2017 Credit Facility,” and to its previous credit facility as the “2016 Credit Facility.” The 2017 Credit Facility increased the Company’s aggregate borrowing commitments from approximately $1.2 billion to $1.5 billion, which amount was initially composed of $1.1 billion of revolving commitments and a term loan in the aggregate principal amount of $400 million. The 2017 Credit Facility matures on February 22, 2022. Under the amended and restated Credit Facility, the term loan is subject to amortization in quarterly principal installments. The initial installment of $3.1 million was paid in December 2017. Beginning in March 2018, the quarterly installment will be $5.0 million. The quarterly principal installments are subject to adjustment for additional term loans and, if applicable, for certain prepayments.

The 2017 Credit Facility allows the Company to borrow either in Canadian dollars and/or Mexican pesos up to an aggregate equivalent amount of $300 million. The maximum amount available for letters of credit under the 2017 Credit Facility is $650 million, of which up to $200 million can be denominated in either Canadian dollars and/or Mexican pesos. The Credit Facility also provides for swing line loans of up to $75 million, and, subject to certain conditions, the Company has the option to increase revolving commitments and/or establish additional term loan tranches up to an aggregate amount of $250 million. Subject to the terms and conditions described in the Credit Facility, these additional term loan tranches may rank equal or junior in respect of right of payment and/or collateral to the Credit Facility, and may have terms and pricing that differ from the 2017 Credit Facility. Borrowings under the Credit Facility are used for working capital requirements, capital expenditures and other corporate purposes, including equity investments, potential acquisitions or other strategic arrangements, the repurchase or prepayment of indebtedness and share repurchases.

Outstanding revolving loans and the term loan under the Credit Facility bear interest, at the Company’s option, at a rate equal to either (a) a Eurocurrency Rate, as defined in the 2017 Credit Facility, plus a margin of 1.25% to 2.00% (under the 2016 Credit Facility, the margin was from 1.00% to 2.00%), or (b) a Base Rate, as defined in the 2017 Credit Facility, plus a margin of 0.25% to 1.00% (under the 2016 Credit Facility, the margin was from 0.00% to 1.00%). The Base Rate equals the highest of (i) the Federal Funds Rate, as defined in the Credit Facility, plus 0.50%, (ii) Bank of America’s prime rate, and (iii) the Eurocurrency Rate plus 1.00%. Financial standby letters of credit and commercial letters of credit issued under the 2017 Credit Facility are subject to a letter of credit fee of 1.25% to 2.00% (under the 2016 Credit Facility, the letter of credit fee was from 1.00% to 2.00%), and performance standby letters of credit are subject to a letter of credit fee of 0.50% to 1.00% under the Credit Facility. The Company must also pay a commitment fee to the lenders of 0.20% to 0.40% on any unused availability under the Credit Facility. In each of the foregoing cases, the applicable margin or fee is based on the Company’s Consolidated Leverage Ratio, as defined in the Credit Facility, as of the then most recent fiscal quarter.

As of December 31, 2017 and 2016, outstanding revolving loans, which included $117 million and $119 million, respectively, of borrowings denominated in foreign currencies, accrued interest at weighted average rates of approximately 3.69% and 3.71% per annum, respectively. The term loan accrued interest at a rate of 3.07% and 2.77% as of December 31, 2017 and 2016, respectively. Letters of credit of approximately $157.1 million and $314.3 million were issued as of December 31, 2017 and 2016, respectively. As of December 31, 2017 and 2016, letters of credit fees accrued at 0.625% and 1.00% per annum, respectively, for performance standby letters of credit, and at 1.50% and 2.00% per annum, respectively, for financial standby letters of credit. Outstanding letters of credit mature at various dates and most have automatic renewal provisions, subject to prior notice of cancellation. As of December 31, 2017 and 2016, availability for revolving loans totaled $565.2 million and $405.9 million, respectively, or up to $492.9 million and $335.7 million, respectively, for new letters of credit. Revolving loan borrowing capacity included $183.4 million and $80.9 million of availability in either Canadian dollars or Mexican pesos as of December 31, 2017 and 2016, respectively. The unused facility fee as of December 31, 2017 and 2016 accrued at a rate of 0.25% and 0.40%, respectively.

The Credit Facility is guaranteed by certain subsidiaries of the Company (the “Guarantor Subsidiaries”) and the obligations under the Credit Facility are secured by substantially all of the Company’s and the Guarantor Subsidiaries’ respective assets, subject to certain exceptions. Under the Credit Facility, if the “Loan Party EBITDA,” as defined in the Credit Facility, as of the last four consecutive fiscal quarters does not represent at least 70% of the “Adjusted Consolidated EBITDA,” as defined in the Credit Facility, for such period, then the Company must designate additional subsidiaries as Guarantor Subsidiaries, and cause them to join the applicable guaranty and security agreements to the Credit Facility. Additionally, any domestic subsidiary with consolidated EBITDA of at least 15% of the Adjusted Consolidated EBITDA must become a Guarantor Subsidiary and join the applicable guaranty and security agreements.

The Credit Facility requires that the Company maintain a Maximum Consolidated Leverage Ratio, as defined in the Credit Facility, of 3.50 (subject to the Acquisition Adjustment described below). The Credit Facility also requires that the Company maintain a Minimum Consolidated Interest Coverage Ratio, as defined in the Credit Facility, of 3.00. The Credit Facility provides that, for purposes of calculating the Consolidated Leverage Ratio, certain cash charges may be added back to the calculation of Consolidated EBITDA, as defined in the Credit Facility, and funded indebtedness excludes undrawn standby performance letters of credit and is further reduced by unrestricted cash over certain thresholds. Additionally, notwithstanding the terms discussed above, subject to certain conditions, if a permitted acquisition or series of permitted acquisitions having consideration exceeding $50 million occurs during a fiscal quarter, the Consolidated Leverage Ratio may be temporarily increased to up to 3.75 during such fiscal quarter and the subsequent two fiscal quarters. Such right may be exercised no more than two times during the term of the Credit Facility. Subject to customary exceptions, the Credit Facility limits the borrowers’ and the Guarantor Subsidiaries’ ability to engage in certain activities, including acquisitions, mergers and consolidations, debt incurrence, investments, capital expenditures, asset sales, debt prepayments, lien incurrence and the making of distributions or repurchases of capital stock. However, distributions payable solely in capital stock are permitted. The Credit Facility provides for customary events of default and carries cross-default provisions with the Company’s other significant debt instruments, including the Company’s indemnity agreement with its surety provider, as well as customary remedies, including the acceleration of repayment of outstanding amounts and other remedies with respect to the collateral securing the Credit Facility obligations.

Other Credit Facilities. The Company has other credit facilities that support the working capital requirements of its foreign operations. Borrowings under these credit facilities, which have varying dates of maturity and are generally renewed on an annual basis, are denominated in Canadian dollars. As of December 31, 2017 and 2016, maximum borrowing capacity totaled Canadian $20.0 million and $40.0 million, respectively, or approximately $15.9 million and $29.8 million, respectively. As of December 31, 2017 and 2016, outstanding borrowings totaled approximately $10.4 million and $13.4 million, respectively, and accrued interest at a weighted average rate of approximately 4.0% and 3.6%, respectively. Outstanding borrowings that are not renewed are repaid with borrowings under the Credit Facility. Accordingly, the carrying amounts of the Company’s borrowings under its other credit facilities, which are included within other debt obligations in the table above, are classified within long-term debt in the Company’s consolidated balance sheets. The Company’s other credit facilities are subject to customary provisions and covenants.

4.875% Senior Notes

The Company has $400 million of 4.875% Senior Notes due March 15, 2023, which were issued in 2013 in a registered public offering. Interest on the 4.875% Senior Notes is payable on March 15 and September 15 of each year. The 4.875% Senior Notes are senior unsecured unsubordinated obligations and rank equal in right of payment with existing and future unsubordinated debt, and rank senior in right of payment to existing and future subordinated debt and are fully and unconditionally guaranteed on an unsecured, unsubordinated, joint and several basis by certain of the Company’s existing and future 100%-owned direct and indirect domestic subsidiaries that are each guarantors of the Credit Facility or other outstanding indebtedness. See Note 17 - Supplemental Guarantor Condensed Consolidating Financial Information. The 4.875% Senior Notes are effectively junior to MasTec’s secured debt, including the Credit Facility and the Term Loan, to the extent of the value of the assets securing that debt.

The Company has the option to redeem all or a portion of the 4.875% Senior Notes at any time on or after March 15, 2018 at the redemption prices set forth in the indenture that governs the 4.875% Senior Notes (the “4.875% Senior Notes Indenture”) plus accrued and unpaid interest, if any, to the redemption date. At any time prior to March 15, 2018, the Company may redeem all or a part of the 4.875% Senior Notes at a redemption price equal to 100% of the principal amount of 4.875% Senior Notes redeemed plus an applicable premium, as defined in the 4.875% Senior Notes Indenture, together with accrued and unpaid interest, if any, to the redemption date. The 4.875% Senior Notes Indenture, among other things, generally limits the ability of the Company and certain of its subsidiaries, subject to certain exceptions, to (i) incur additional debt and issue preferred stock, (ii) create liens, (iii) pay dividends, acquire shares of capital stock, make payments on subordinated debt or make investments, (iv) place limitations on distributions from certain subsidiaries, (v) issue guarantees, (vi) issue or sell the capital stock of certain subsidiaries, (vii) sell assets, (viii) enter into transactions with affiliates and (ix) effect mergers. The 4.875% Senior Notes Indenture provides for customary events of default, as well as customary remedies upon an event of default, as defined in the 4.875% Senior Notes Indenture, including acceleration of repayment of outstanding amounts.

Debt Covenants

MasTec was in compliance with the provisions and covenants of its outstanding debt instruments as of December 31, 2017 and 2016.

Contractual Maturities of Debt and Capital Lease Obligations

Contractual maturities of MasTec’s debt and capital lease obligations as of December 31, 2017 were as follows (in millions):



2018	$	88.3
2019	65.5
2020	57.0
2021	46.4
2022	724.4
Thereafter	400.0
Total	$	1,381.6

As of December 31, 2017 and 2016, accrued interest payable, which is recorded within other accrued expenses in the consolidated balance sheets, totaled $7.4 million, and $8.5 million, respectively.

Lease Obligations

12 Months Ended

Dec. 31, 2017

Leases [Abstract]

Lease Obligations

Note 8 - Lease Obligations

Capital Leases

MasTec enters into agreements that provide lease financing for machinery and equipment. Leases meeting certain criteria are capitalized, with the related asset recorded in property and equipment and a corresponding amount recorded within the Company’s debt obligations. Capital lease additions are reflected in the consolidated statements of cash flows within the supplemental disclosures of non-cash information. The gross amount of assets held under capital leases as of December 31, 2017 and 2016, which are included within property and equipment, net, totaled $418.0 million and $294.9 million, respectively. Assets held under capital leases, net of accumulated depreciation, totaled $277.3 million and $177.5 million as of December 31, 2017 and 2016, respectively.

Operating Leases

In the ordinary course of business, the Company enters into non-cancelable operating leases for certain of its facility, vehicle and equipment needs, including related party leases. See Note 15 - Related Party Transactions. These leases allow the Company to conserve cash and provide flexibility in that the Company pays a monthly rental fee for the use of related facilities, vehicles and equipment rather than purchasing them. The terms of these agreements vary from lease to lease, including some with renewal options and escalation clauses. The Company may decide to cancel or terminate a lease before the end of its term, in which case the Company is typically liable for the remaining lease payments under the term of the lease. For operating leases with purchase options, the option to purchase equipment is at estimated fair market value. Rent and related expense for operating leases that have non-cancelable terms in excess of one year totaled approximately $104.2 million, $100.5 million and $81.8 million for the years ended December 31, 2017, 2016 and 2015, respectively. The Company also incurred rent and related expense for facilities, vehicles and equipment having original terms of one year or less totaling approximately $461.0 million, $298.0 million and $196.2 million for the years ended December 31, 2017, 2016 and 2015, respectively.

Future Lease Commitments

Future minimum lease commitments under capital leases and non-cancelable operating leases, including escalation clauses in effect as of December 31, 2017, were as follows (in millions):



	Capital Leases			Operating Leases
2018	$	69.5		$	90.7
2019	49.4			57.3
2020	39.4			33.9
2021	29.0			19.2
2022	9.1			12.3
Thereafter	—			30.3
Total minimum lease payments	$	196.4		$	243.7
Less amounts representing interest	(15.2		)
Total capital lease obligations, net of interest	$	181.2
Less current portion	(63.5		)
Long-term portion of capital lease obligations, net of interest	$	117.7

Stock-Based Compensation and Other Employee Benefit Plans

12 Months Ended

Dec. 31, 2017

Share-based Compensation [Abstract]

Stock-Based Compensation and Other Employee Benefit Plans

Note 9 – Stock-Based Compensation and Other Employee Benefit Plans

The Company’s stock-based compensation plans, under which shares of the Company’s common stock are reserved for issuance, include: the MasTec, Inc. 2013 Incentive Compensation Plan (as amended from time to time, the “2013 Incentive Plan”), the MasTec, Inc. Bargaining Units Employee Stock Purchase Plan (the “2013 Bargaining Units ESPP”) and the MasTec, Inc. 2011 Amended and Restated Employee Stock Purchase Plan (the “2011 ESPP,” and, together with the 2013 Bargaining Units ESPP, the “ESPPs”). The 2013 Incentive Plan permits a total of approximately 7,391,000 shares of the Company’s common stock to be issued. Under the Company’s ESPPs, shares of the Company’s common stock are available for purchase by eligible employees, which collectively permit the issuance of up to 3,000,000 new shares of MasTec, Inc. common stock. Under all stock-based compensation plans in effect as of December 31, 2017, including employee stock purchase plans, there were approximately 4,811,000 shares available for future grant. In 2017, the 2013 Incentive Compensation Plan was amended to revise the amount of tax the Company can withhold for employee tax withholdings on share-based awards, as provided under ASU 2016-09.

Restricted Shares

MasTec grants restricted stock awards and restricted stock units to eligible employees and directors, which are valued based on the closing market share price of MasTec common stock (the “market price”) on the date of grant. During the restriction period, holders of restricted stock awards are entitled to vote the shares. Total unearned compensation related to restricted shares as of December 31, 2017 was approximately $20.4 million, which is expected to be recognized over a weighted average period of approximately 1.5 years. The intrinsic value of restricted shares that vested, which is based on the market price on the date of vesting, totaled $39.7 million, $3.5 million and $8.1 million, respectively, for the years ended December 31, 2017, 2016 and 2015.



Activity, restricted shares: ^(a)	Restricted Shares		Per Share Weighted Average Grant Date Fair Value
Non-vested restricted shares, as of December 31, 2015	1,630,232		$	22.94
Granted	637,332		17.69
Vested	(188,386	)	20.42
Canceled/forfeited	(108,592	)	20.71
Non-vested restricted shares, as of December 31, 2016	1,970,586		$	21.61
Granted	429,061		40.46
Vested	(899,815	)	28.08
Canceled/forfeited	(51,241	)	18.22
Non-vested restricted shares, as of December 31, 2017	1,448,591		$	23.29


(a)	Includes 27,550, 43,300 and 32,250 restricted stock units as of December 31, 2017, 2016 and 2015, respectively.

Employee Stock Purchase Plans

The following table provides details pertaining to the Company’s ESPPs for the periods indicated:



	For the Years Ended December 31,
	2017		2016		2015
Cash proceeds (in millions)	$	3.3	$	2.7	$	2.0
Common shares issued	92,145		144,183		134,389
Weighted average price per share	$	35.92	$	18.55	$	14.67
Weighted average per share grant date fair value	$	9.24	$	5.00	$	4.22

Stock Options

The Company previously granted options to purchase its common stock to employees and members of the Board of Directors and affiliates under various stock option plans. During 2016, all 202,700 remaining stock options under the previous grants were exercised at a weighted average exercise price of $13.06. The intrinsic value of options exercised, which is the difference between the exercise price and the market share price of the Company’s common stock on the date of exercise, totaled $1.8 million and $0.8 million for the years ended December 31, 2016 and 2015, respectively. Proceeds from options exercised, net of shares withheld in cashless option exercises, totaled $2.1 million and $0.5 million for the years ended December 31, 2016 and 2015, respectively.

Non-Cash Stock-Based Compensation Expense

Details of non-cash stock-based compensation expense and related tax effects for the periods indicated were as follows (in millions):



	For the Years Ended December 31,
	2017		2016		2015
Non-cash stock-based compensation expense	$	15.7	$	15.1	$	12.4
Income Tax Effects:
Income tax effect of non-cash stock-based compensation	$	11.2	$	5.6	$	4.2
Excess tax benefit from non-cash stock-based compensation ^(a)	$	5.7	$	0.1	$	0.1


(a)	Excess tax benefits represent cash flows from tax deductions in excess of the tax effect of compensation expense associated with share-based payment arrangements. For the year ended December 31, 2017, the Company recognized a tax benefit of $5.4 million, net of tax deficiencies, related to the vesting of share-based payment awards.

401(k) Plan. MasTec has a 401(k) plan covering all eligible employees. Subject to certain dollar limits, eligible employees may contribute up to 75% of their pre-tax annual compensation to the 401(k) plan. The Company’s matching contribution is equal to 100% of the first 3% of the employee’s salary and 50% of the next 2% of the employee’s salary, up to a maximum 4% employer match. Discretionary matching contributions, which are payable 50% in shares of MasTec common stock and 50% in cash, are paid quarterly. During the years ended December 31, 2017, 2016 and 2015, matching contributions totaled approximately $11.9 million, $11.1 million and $10.2 million, respectively.

Deferred Compensation Plans. MasTec offers a deferred compensation plan to its highly compensated employees. These employees are allowed to contribute a percentage of their pre-tax annual compensation to the deferred compensation plan. The Company also offers a deferred compensation plan to its Board of Directors, under which directors may elect to defer the receipt of compensation for their services. Total deferred compensation plan assets, which are included within other long-term assets in the consolidated balance sheets, totaled $9.4 million and $7.7 million as of December 31, 2017 and 2016, respectively. Total deferred compensation plan liabilities, which are included within other long-term liabilities in the consolidated balance sheets, totaled $9.7 million and $7.6 million as of December 31, 2017 and 2016, respectively.

Other Retirement Plans

12 Months Ended

Dec. 31, 2017

Multiemployer Plans [Abstract]

Other Retirement Plans

Note 10 – Other Retirement Plans

Multiemployer Plans.

As discussed in Note 1 - Business, Basis of Presentation and Significant Accounting Policies, certain of MasTec’s subsidiaries are party to various collective bargaining agreements with unions representing certain of their employees, which require the Company to pay specified wages, provide certain benefits to their union employees and contribute certain amounts to MEPPs. The PPA defines the funding rules for defined benefit pension plans and establishes funding classifications for U.S.-registered multiemployer pension plans. Under the PPA, plans are classified into one of the following five categories, based on multiple factors, also referred to as a plan’s “zone status”: Green (safe), Yellow (endangered), Orange (seriously endangered), and Red (critical or critical and declining). Factors included in the determination of a plan’s zone status include: funded percentage, cash flow position and whether the plan is projecting a minimum funding deficiency.

A multiemployer plan that is so underfunded as to be in “endangered,” “seriously endangered,” “critical,” or “critical and declining” status (as determined under the PPA) is required to adopt a funding improvement plan (“FIP”) or a rehabilitation plan (“RP”), which, among other actions, could include decreased benefits and increased employer contributions, which could take the form of a surcharge on benefit contributions. These actions are intended to improve their funding status over a period of years. If a pension fund is in critical status, a participating employer must pay an automatic surcharge in addition to contributions otherwise required under the collective bargaining agreement (“CBA”). With some exceptions, the surcharge is equal to 5% of required contributions for the initial critical year and 10% for each succeeding plan year in which the plan remains in critical status. The surcharge ceases on the effective date of a CBA (or other agreement) that includes contribution and benefit terms consistent with the rehabilitation plan. Certain plans in which the Company participates are in “endangered,” “seriously endangered,” “critical,” or “critical and declining” status. The amount of additional funds, if any, that the Company may be obligated to contribute to these plans in the future cannot be estimated due to the uncertainty of the future levels of work that could be required of the union employees covered by these plans, as well as the required future contribution rates and possible surcharges applicable to these plans. See Note 14 - Commitments and Contingencies for additional information.

Details of significant multiemployer pension plans as of and for the periods indicated, based upon information available to the Company from plan administrators as well as publicly available information on the U.S. Department of Labor website, are provided in the following table:

Contributions

(in millions)

For the Years Ended December 31,

Pension Protection Act Zone Status

Multiemployer Pension Plan

Employer Identification Number

Plan Number

2017

2016

2015

Expiration Date of CBA

2017

As of

2016

As of

FIP/RP Status

Surcharge

Pipeline Industry Pension Fund

736146433

001

28.8

15.9

2.5

05/31/2020

Green

12/31/2016

(a)

Green

12/31/2015

(a)

Central Pension Fund of the IUOE and Participating Employers

366052390

001

21.6

19.3

5.7

06/01/2020

Green

01/31/2017

Green

01/31/2016

Teamsters National Pipe Line Pension Plan

461102851

001

7.6

3.6

1.4

05/31/2020

Green

12/31/2016

(a)

Green

12/31/2015

(a)

Ohio Operating Engineers Pension Plan

316129968

001

4.9

—

06/01/2020

Green

07/31/2016

Green

07/31/2015

Laborers' National Pension Fund

751280827

001

3.5

3.0

0.8

05/31/2020

Green

12/31/2016

Green

12/31/2015

West Virginia Laborers' Pension Trust Fund

556026775

001

3.0

0.5

1.4

05/31/2020

Green

03/31/2017

Green

03/31/2016

(a)

Laborers' District Council & Contractors Pension Fund of Ohio

316129964

001

2.5

0.5

0.2

05/31/2020

Green

12/31/2016

Green

12/31/2015

International Union of Operating Engineers Local 132 Pension Fund

556015364

001

2.3

0.2

1.9

06/01/2020

Green

03/31/2017

Green

03/31/2016

(a)

Operating Engineers Local 324 Pension Fund

381900637

001

2.1

—

06/01/2020

Red

04/30/2017

Red

04/30/2016

Implemented

Michigan Laborers' Pension Plan

386233976

001

2.0

1.1

0.8

05/31/2020

Yellow

08/31/2017

Yellow

08/31/2016

(b)

Implemented

National Electrical Benefit Fund

530181657

001

1.8

1.7

1.4

Varies through 09/06/2020

Green

12/31/2016

Green

12/31/2015

Laborers' Local Union No. 158 Pension Plan

236580323

001

1.8

0.4

0.7

05/31/2020

Green

12/31/2016

Green

12/31/2015

(a)

IBEW Local 1249 Pension Plan

156035161

001

1.5

1.1

1.0

05/02/2021

Yellow

12/31/2016

Yellow

12/31/2015

Implemented

Central Laborers' Pension Fund

376052379

001

0.5

2.6

—

05/31/2020

Yellow

12/31/2016

(b)

Red

12/31/2015

(b)

Implemented

Other funds

8.2

(c)

10.0

(c)

6.0

(c)

Total multiemployer pension plan contributions

92.1

59.9

23.8


(a)	The Company’s contributions to this plan represent greater than 5% of the plan’s total contributions.


(b)	This plan has utilized extended amortization provisions, which provide plans with extensions of time to amortize pension funding shortfalls.

(c)

The 2017, 2016 and 2015 contributions include approximately $0.7 million, $0.9 million and $1.4 million, respectively, for Canadian multiemployer pension plans. Canadian multiemployer pension plans are not subject to the provisions of ERISA or the funding rules under the PPA that apply to U.S. registered multiemployer pension plans. Contributions to Canadian multiemployer pension plans are based on fixed amounts per hour per employee for employees covered under these plans.

Total contributions to multiemployer plans, and the related number of employees covered by these plans, including with respect to the Company’s Canadian operations for the periods indicated, were as follows:



	Multiemployer Plans
	Covered Employees		Contributions (in millions)
For the Years Ended December 31:	Low	High	Pension		Other Multiemployer		Total
2017	550	7,057	$	92.1	$	10.3	$	102.4
2016	550	4,910	$	59.9	$	10.1	$	70.0
2015	590	2,463	$	23.8	$	9.0	$	32.8

The number of union employees employed at any given time varies depending upon the location and number of ongoing projects and the need for union resources in connection with those projects. The fluctuations in the number of employees covered under multiemployer plans and related contributions in the tables above are primarily related to higher levels of union resource-based project activity within the Company’s oil and gas operations.

Equity

12 Months Ended

Dec. 31, 2017

Equity [Abstract]

Equity

Note 11 – Equity

Share Activity

In February 2016, the Company’s Board of Directors authorized a $100 million share repurchase program (the “2016 Share Repurchase Program”). Under the 2016 Share Repurchase Program, which does not have an expiration date, the Company may repurchase shares from time to time in open market transactions or in privately-negotiated transactions in accordance with applicable securities laws. The timing and the amount of any repurchases will be determined based on market conditions, legal requirements, cash flow and liquidity needs and other factors. The share repurchase program may be modified or suspended at any time at the Company’s discretion. Share repurchases, which are recorded at cost and are held in the Company’s treasury, are funded with available cash or with availability under the Credit Facility. The Company repurchased 38.8 thousand shares of the Company’s common stock for an aggregate purchase price of $1.6 million under this program during the year ended December 31, 2017, and no shares were repurchased during the year ended December 31, 2016. During the year ended December 31, 2015, the Company repurchased 5.2 million shares of its common stock under a separate and completed share repurchase program that was established in 2014 for an aggregate purchase price of $100 million.

The Company may use either authorized and unissued shares or treasury shares to meet share issuance requirements, including those resulting from vesting of restricted shares and other share issuance requirements.

Comprehensive Income (Loss)

Comprehensive income (loss) is a measure of net income (loss) and other changes in equity that result from transactions other than those with shareholders. Comprehensive income (loss) consists of net income (loss), foreign currency translation adjustments, primarily from fluctuations in foreign currency exchange rates of the Company’s foreign subsidiaries with a functional currency other than the U.S. dollar, unrealized gains and losses from investment activities and net income (loss) attributable to non-controlling interests.

Accumulated Other Comprehensive Loss

Accumulated other comprehensive loss is composed of unrealized foreign currency gains and losses and unrealized gains and losses from certain investment activities. Unrealized foreign currency activity for the three years in the period ended December 31, 2017 is primarily related to translation gains and losses resulting from the Company’s Canadian operations. Investment activity for the years ended December 31, 2017 and 2016 relates to unrealized gains and losses on interest rate swaps associated with the Waha JVs.

Activity for the periods indicated was as follows (in thousands):



	For the Years Ended December 31,
	2017									2016									2015
	Foreign Currency			Other			Total			Foreign Currency			Other			Total			Foreign Currency			Other			Total
Balance as of January 1	$	(64,478	)	$	(1,336	)	$	(65,814	)	$	(67,063	)	$	(5,288	)	$	(72,351	)	$	(28,716	)	$	(5,288	)	$	(34,004	)
Unrealized gains (losses), net of tax	1,627			475			2,102			2,585			3,952			6,537			(38,347		)	—			(38,347		)
Balance as of December 31	$	(62,851	)	$	(861	)	$	(63,712	)	$	(64,478	)	$	(1,336	)	$	(65,814	)	$	(67,063	)	$	(5,288	)	$	(72,351	)

Income Taxes

12 Months Ended

Dec. 31, 2017

Income Tax Disclosure [Abstract]

Income Taxes

Note 12 - Income Taxes

The components of income (loss) before income taxes for the periods indicated were as follows (in millions):



	For the Years Ended December 31,
	2017		2016		2015
Domestic	$	334.9	$	202.4	$	(26.5	)
Foreign	36.9		23.4		(41.2		)
Total	$	371.8	$	225.8	$	(67.7	)

The provision for income taxes for the periods indicated were as follows (in millions):



	For the Years Ended December 31,
	2017			2016			2015
Current:
Federal	$	(6.0	)	$	85.8		$	(4.5	)
Foreign	11.5			3.0			9.4
State and local	(0.8		)	6.7			3.3
	$	4.7		$	95.5		$	8.2
Deferred:
Federal	$	18.2		$	6.1		$	25.7
Foreign	(7.5		)	(6.8		)	(19.9		)
State and local	7.6			(3.0		)	(2.0		)
	$	18.3		$	(3.7	)	$	3.8
Provision for income taxes	$	22.9		$	91.8		$	12.0

The tax effects of significant items comprising the Company’s net deferred tax liability as of the dates indicated were as follows (in millions):



	December 31,
	2017			2016
Deferred tax assets:
Accrued insurance	$	24.6		$	31.1
Operating loss carryforwards and tax credits	54.9			34.9
Unrealized gains and losses	11.4			26.3
Compensation and benefits	7.5			24.1
Bad debt	1.2			4.7
Other	7.9			12.4
Valuation allowance	(40.5		)	(21.4		)
Total deferred tax assets	$	67.0		$	112.1
Deferred tax liabilities:
Property and equipment	$	104.1		$	126.6
Goodwill	56.7			72.8
Other intangible assets	28.7			32.9
Gain on remeasurement of equity investee	6.9			10.9
Long-term contracts	11.3			20.2
Investments in unconsolidated entities	52.8			0.0
Other	11.0			15.3
Total deferred tax liabilities	$	271.5		$	278.7
Net deferred tax liabilities	$	(204.5	)	$	(166.6	)

As of December 31, 2017, the Company had $204.5 million of long-term deferred tax liabilities. As of December 31, 2016, current deferred tax assets, net, totaled $11.8 million and long-term deferred tax liabilities, net, totaled $178.4 million. See Note 1 - Business, Basis of Presentation and Significant Accounting Policies regarding the January 1, 2017 adoption of ASU 2015-17, Income Taxes (Topic 740): Balance Sheet Classification of Deferred Taxes.

In assessing the ability to realize the deferred tax assets, management considers whether it is more likely than not that some portion or all of the deferred tax assets will not be realized. The ultimate realization of deferred tax assets is dependent upon the generation of future taxable income during the periods in which these temporary differences become deductible. Management considers the projected future taxable income and prudent and feasible tax planning strategies in making this assessment. The Company’s valuation allowances as of December 31, 2017 and 2016 are related primarily to foreign net operating losses and deferred tax assets. The Company’s state net operating loss carryforwards, which may be carried forward between 5 and 20 years depending on the jurisdiction, totaled approximately $12.3 million and $9.0 million as of December 31, 2017 and 2016, respectively. The Company’s foreign net operating loss carryforwards, which are primarily related to the Company’s Canadian operations, totaled approximately $38.4 million and $22.7 million as of December 31, 2017 and 2016, respectively. The Canadian net operating loss carryforwards, which make up the majority of the foreign net operating loss carryforwards, begin to expire in 2033. The Company’s federal net operating loss carryforwards, which begin to expire in 2022, totaled approximately $0.2 million and $0.5 million as of December 31, 2017 and 2016, respectively.

In December 2017, the 2017 Tax Act was enacted, which includes broad tax reform that is applicable to the Company. Under the provisions of the 2017 Tax Act, the U.S. corporate tax rate decreased from 35% to 21% effective January 1, 2018. As a result, the Company’s U.S. deferred income tax balances were required to be remeasured in 2017. The Company completed an initial remeasurement of its deferred tax assets and liabilities as of December 31, 2017 as a result of this new tax law, which resulted in a non-cash tax benefit of $120.1 million for the year ended December 31, 2017. This initial remeasurement calculation contains estimates of the impact of the 2017 Tax Act as permitted under SAB 118. These amounts are considered provisional and may be affected by future guidance. The Company may identify additional remeasurement adjustments to its recorded deferred tax assets and liabilities. Any such revisions will be treated in accordance with the measurement period guidance outlined in SAB 118.

As of December 31, 2017, the Company has not made a provision for U.S. income taxes on unremitted foreign earnings because such earnings, which generally become subject to U.S. taxation upon remittance of dividends and certain other circumstances, are considered to be insignificant and are intended to be indefinitely reinvested outside the United States. The Company expects that domestic cash resources will be sufficient to fund its domestic operations and cash commitments in the future.

A reconciliation of the U.S. statutory federal income tax rate related to pretax income to the effective tax rate for the periods indicated is as follows:



	For the Years Ended December 31,
	2017		2016		2015
U.S. statutory federal rate applied to pretax income (loss)	35.0	%	35.0	%	35.0	%
State and local income taxes, net of federal benefit	2.0		2.6		(1.0	)
Foreign tax rate differential	0.3		(0.1	)	(14.4	)
Non-deductible expenses	2.2		4.4		(13.5	)
Goodwill and intangible assets	(0.0	)	(0.7	)	(17.7	)
Change in tax rate	(32.3	)	(1.9	)	(3.6	)
Domestic production activities deduction	(0.2	)	(2.9	)	(1.0	)
Other	(0.7	)	(0.1	)	(1.4	)
Tax credits	(2.8	)	(0.0	)	(0.0	)
Valuation allowance for deferred tax assets	2.7		4.3		0.0
Effective income tax rate	6.2	%	40.6	%	(17.6	)%

An entity may only recognize or continue to recognize tax positions that meet a "more likely than not" threshold. In the ordinary course of business, there is inherent uncertainty in quantifying income tax positions. The Company assesses its income tax positions and records tax benefits for all years subject to examination based on management's evaluation of the facts, circumstances and information available at the reporting date. For those tax positions where it is more likely than not that a tax benefit will be sustained, the Company has recognized the largest amount of tax benefit with a greater than 50% likelihood of being realized upon ultimate settlement with a taxing authority that has full knowledge of all relevant information. For those income tax positions where it is not more likely than not that a tax benefit will be sustained, no tax benefit has been recognized in the Company's financial statements.

A reconciliation of the beginning and ending amount of uncertain tax positions including interest and penalties is as follows (in millions):



	For the Years Ended December 31,
	2017		2016		2015
Beginning balance	$	—	$	—	$	—
Additions based on tax positions related to the current year	3.2		—		—
Additions for tax positions of prior years	4.9		—		—
Ending balance	$	8.1	$	—	$	—

The Company classifies interest and penalties on uncertain tax positions as a component of income tax expense in the consolidated statements of operations, which amounts were de minimis in 2017. If the Company were to recognize its gross unrecognized tax benefits as of December 31, 2017, approximately $8.1 million, including interest and penalties, would affect the Company’s effective tax rate.

The IRS has completed examinations of the Company’s federal income tax returns through the calendar year 2013 and has recently begun an examination of the Company’s 2015 federal income tax return. Certain state taxing authorities are examining various years. The final outcome of these examinations is not yet determinable. With few exceptions, as of December 31, 2017, the Company is no longer subject to state examinations by taxing authorities for years before 2014.

Segments and Related Information

12 Months Ended

Dec. 31, 2017

Segment Reporting [Abstract]

Segments and Related Information

Note 13 - Segments and Related Information

Segment Discussion

MasTec manages its operations under five operating segments, which represent MasTec’s five reportable segments: (1) Communications; (2) Oil and Gas; (3) Electrical Transmission; (4) Power Generation and Industrial and (5) Other. This structure is generally focused on broad end-user markets for MasTec’s labor-based construction services. All five reportable segments derive their revenue from the engineering, installation and maintenance of infrastructure, primarily in North America.

The Communications segment performs engineering, construction, maintenance and customer fulfillment activities related to communications infrastructure, primarily for wireless and wireline/fiber communications and install-to-the-home customers, and, to a lesser extent, infrastructure for utilities, among others. MasTec performs engineering, construction and maintenance services on oil and natural gas pipelines and processing facilities for the energy and utilities industries through its Oil and Gas segment. The Electrical Transmission segment primarily serves the energy and utility industries through the engineering, construction and maintenance of electrical transmission lines and substations. The Power Generation and Industrial segment primarily serves energy, utility and other end-markets through the installation and construction of conventional and renewable power facilities, related electrical transmission infrastructure, ethanol/biofuel facilities and various types of heavy civil and industrial infrastructure. The Other segment includes equity investees, the services of which vary from those provided by the Company’s four primary segments, as well as other small business units that perform construction and other services for a variety of international end-markets.

The accounting policies of the reportable segments are the same as those described in Note 1 - Business, Basis of Presentation and Significant Accounting Policies. Intercompany revenue and costs among the reportable segments are de minimis and accounted for as if the sales were to third parties because these items are based on negotiated fees between the segments involved. All intercompany transactions and balances are eliminated in consolidation. Intercompany revenue and costs between entities within a reportable segment are eliminated to arrive at segment totals. Eliminations between segments are separately presented. Corporate results include amounts related to Corporate functions such as administrative costs, professional fees, acquisition-related transaction costs (exclusive of acquisition integration costs, which are included within the segment results of the acquired business), and other discrete items, such as goodwill and intangible asset impairment. Segment results include certain allocations of centralized costs such as general liability, medical and workers’ compensation insurance and certain information technology costs. Income tax expense is managed by Corporate on a consolidated basis and is not allocated to the reportable segments.

Earnings before interest, taxes, depreciation and amortization (“EBITDA”) is the measure of profitability used by management to manage its segments and, accordingly, in its segment reporting. As appropriate, the Company supplements the reporting of consolidated financial information determined in accordance with U.S. GAAP with certain non-U.S. GAAP financial measures, including EBITDA. The Company believes these non-U.S. GAAP measures provide meaningful information and help investors understand the Company’s financial results and assess its prospects for future performance. The Company uses EBITDA to evaluate its performance, both internally and as compared with its peers, because it excludes certain items that may not be indicative of the Company’s core operating results for its reportable segments, as well as items that can vary widely across different industries or among companies within the same industry, and for non-cash stock-based compensation expense, can also be subject to volatility from changes in the market price per share of our common stock or variations in the value of shares granted. Segment EBITDA is calculated in a manner consistent with consolidated EBITDA.

For the years ended December 31, 2017, 2016 and 2015, Other segment EBITDA included project losses of $7.9 million, $5.1 million and $16.3 million, respectively, from a proportionately consolidated non-controlled Canadian joint venture, which is managed by a third party, and for which we have minimal direct construction involvement. For the year ended December 31, 2016, EBITDA for the Oil and Gas and Electrical Transmission segments included first quarter project losses of $13.5 million and $15.1 million, respectively, and restructuring charges of $6.3 million and $8.9 million, respectively. For the year ended December 31, 2015, Communications segment EBITDA included $17.8 million of acquisition integration costs, Electrical Transmission segment EBITDA included a $12.2 million charge relating to a court mandated mediation settlement, and Power Generation and Industrial segment EBITDA included project losses of $21.4 million. In addition, for the year ended December 31, 2015, Corporate segment EBITDA included $78.6 million of goodwill and intangible asset impairment and $16.5 million of Audit Committee independent investigation costs.

Summarized financial information for MasTec’s reportable segments is presented and reconciled to consolidated financial information for total MasTec, including a reconciliation of consolidated income (loss) before income taxes to EBITDA, in the following tables (in millions). The tables below may contain slight summation differences due to rounding.



	For the Years Ended December 31,
Revenue:	2017			2016			2015
Communications ^(a)	$	2,424.4		$	2,323.6		$	1,973.2
Oil and Gas	3,497.2			2,024.4			1,495.1
Electrical Transmission	378.2			383.8			341.5
Power Generation and Industrial	299.9			405.7			381.6
Other	20.8			15.9			24.1
Eliminations	(13.5		)	(18.7		)	(7.2		)
Consolidated revenue	$	6,607.0		$	5,134.7		$	4,208.3


(a)	Revenue generated primarily by utilities customers represented 13.4%, 11.1% and 10.6% of Communications segment revenue for the years ended December 31, 2017, 2016 and 2015, respectively.



	For the Years Ended December 31,
EBITDA:	2017			2016			2015
Communications	$	247.4		$	244.6		$	194.8
Oil and Gas	402.2			297.3			157.0
Electrical Transmission	17.6			(42.9		)	(71.3		)
Power Generation and Industrial	22.6			18.3			8.8
Other	19.8			(2.6		)	(18.8		)
Corporate	(88.7		)	(73.1		)	(120.5		)
Consolidated EBITDA	$	620.9		$	441.5		$	150.0



	For the Years Ended December 31,
Depreciation and Amortization:	2017		2016		2015
Communications	$	53.2	$	50.3	$	50.6
Oil and Gas	96.7		78.4		84.5
Electrical Transmission	22.8		23.2		21.1
Power Generation and Industrial	9.1		6.2		6.6
Other	0.1		0.1		0.1
Corporate	6.1		6.7		6.8
Consolidated depreciation and amortization	$	188.0	$	164.9	$	169.7



	As of December 31,
Assets:	2017		2016		2015
Communications	$	1,314.4	$	1,156.9	$	1,032.2
Oil and Gas	1,762.6		1,267.2		1,131.4
Electrical Transmission	471.4		419.1		409.1
Power Generation and Industrial	288.6		268.1		252.5
Other	153.2		27.7		34.3
Corporate	76.4		44.1		67.8
Consolidated segment assets	$	4,066.6	$	3,183.1	$	2,927.3



	For the Years Ended December 31,
Capital Expenditures:	2017		2016		2015
Communications	$	40.5	$	28.5	$	25.8
Oil and Gas	57.7		64.0		38.1
Electrical Transmission	14.9		19.8		13.0
Power Generation and Industrial	5.4		3.4		3.5
Other	0.0		0.3		0.2
Corporate	4.9		1.1		3.8
Consolidated capital expenditures	$	123.4	$	117.1	$	84.4



	For the Years Ended December 31,
EBITDA Reconciliation:	2017		2016		2015
Income (loss) before income taxes	$	371.8	$	225.8	$	(67.7	)
Plus:
Interest expense, net	61.0		50.7		48.1
Depreciation and amortization	188.0		164.9		169.7
Consolidated EBITDA	$	620.9	$	441.5	$	150.0

Foreign Operations. MasTec operates in North America, primarily in the United States and Canada, and, to a lesser extent, in Mexico. For the years ended December 31, 2017, 2016 and 2015, revenue of $6.4 billion, $4.9 billion and $3.6 billion, respectively, was derived from U.S. operations, and revenue of $211.5 million, $279.7 million and $574.8 million, respectively, was derived from foreign operations, the majority of which was from the Company’s Canadian operations in the Oil and Gas segment. Long-lived assets held in the U.S. included property and equipment, net, of $649.5 million, $475.3 million and $464.6 million as of December 31, 2017, 2016 and 2015, respectively, and, for the Company’s businesses in foreign countries, the majority of which are in Canada, totaled $57.0 million, $73.8 million and $94.1 million, respectively. Intangible assets and goodwill, net, related to the Company’s U.S. operations totaled approximately $1.2 billion as of December 31, 2017 and $1.1 billion as of both December 31, 2016 and 2015, and, for the Company’s businesses in foreign countries, the majority of which are in Canada, totaled approximately $112.8 million, $107.8 million and $107.3 million, respectively. Amounts due from customers from which foreign revenue was derived accounted for approximately 5%, 8% and 17% of the Company’s consolidated net accounts receivable position, which represents accounts receivable, net, less BIEC, as of December 31, 2017, 2016 and 2015, respectively.

Significant Customers

Revenue concentration information for significant customers as a percentage of total consolidated revenue was as follows:



	For the Years Ended December 31,
	2017	2016	2015
Customer:
Energy Transfer affiliates ^(a)	40%	27%	7%
AT&T (including DIRECTV^®) ^(b)	25%	34%	32%


(a)	The Company's relationship with Energy Transfer affiliates is based upon various construction contracts for pipeline activities with Energy Transfer Partners L.P., and its subsidiaries and affiliates, all of which are consolidated by Energy Transfer Equity, L.P. Revenue from Energy Transfer affiliates is included in the Oil and Gas segment.

(b)

The Company’s relationship with AT&T is based upon multiple separate master service and other service agreements, including for installation and maintenance services, as well as construction/installation contracts for AT&T’s: (i) wireless business; (ii) wireline/fiber businesses; and (iii) various install-to-the-home businesses, including DIRECTV®. Revenue from AT&T is included in the Communications segment.

Commitments and Contingencies	12 Months Ended
Commitments and Contingencies	Dec. 31, 2017
Commitments and Contingencies Disclosure [Abstract]
Commitments and Contingencies	Note 14 - Commitments and Contingencies MasTec is subject to a variety of legal cases, claims and other disputes that arise from time to time in the ordinary course of its business. MasTec cannot provide assurance that it will be successful in recovering all or any of the potential damages it has claimed or in defending claims against the Company. The outcome of such cases, claims and disputes cannot be predicted with certainty and an unfavorable resolution of one or more of them could have a material adverse effect on the Company’s business, financial condition, results of operations and cash flows. Other Commitments and Contingencies Leases. In the ordinary course of business, the Company enters into non-cancelable operating leases for certain of its facility, vehicle and equipment needs, including related party leases. See Note 8 - Lease Obligations and Note 15 - Related Party Transactions. Letters of Credit. In the ordinary course of business, the Company is required to post letters of credit for its insurance carriers, surety bond providers and in support of performance under certain contracts as well as certain obligations associated with the Company’s equity investments, including its variable interest entities. Such letters of credit are generally issued by a bank or similar financial institution. The letter of credit commits the issuer to pay specified amounts to the holder of the letter of credit under certain conditions. If this were to occur, the Company would be required to reimburse the issuer of the letter of credit, which, depending upon the circumstances, could result in a charge to earnings. As of December 31, 2017 and 2016, there were $157.1 million and $314.3 million, respectively, of letters of credit issued under the Company’s Credit Facility. The Company is not aware of material claims relating to its outstanding letters of credit as of December 31, 2017 or 2016. Performance and Payment Bonds. In the ordinary course of business, MasTec is required by certain customers to provide performance and payment bonds for contractual commitments related to projects in process. These bonds provide a guarantee to the customer that the Company will perform under the terms of a contract and that the Company will pay subcontractors and vendors. If the Company fails to perform under a contract or to pay subcontractors and vendors, the customer may demand that the surety make payments or provide services under the bond. The Company must reimburse the surety for expenses or outlays it incurs. As of December 31, 2017 and 2016, outstanding performance and payment bonds totaled $119.7 million and $72.9 million, respectively, and estimated costs to complete projects secured by these bonds totaled $46.0 million and $9.5 million, respectively. These amounts do not include performance and payment bonds associated with the Company’s equity investments. Investment Arrangements. From time to time, the Company may participate in selected investment or strategic arrangements to expand its operations, customer base or geographic reach, including arrangements that combine the Company’s skills and resources with those of others to allow for the performance of particular projects. The Company holds undivided interests, ranging from 85% to 90%, in several proportionately consolidated non-controlled contractual joint ventures that provide infrastructure construction services for electrical transmission projects. The Company also holds a 35% undivided interest in a proportionately consolidated non-controlled Canadian contractual joint venture that was underway when the Company acquired Pacer in 2014, whose sole activity involves the construction of a bridge, a business in which the Company does not otherwise engage. This joint venture, which is managed by a third party, and for which the Company has minimal direct construction involvement, automatically terminates upon completion of the project. Income and/or losses incurred by these joint ventures are generally shared proportionally by the respective joint venture members, with the members of the joint ventures jointly and severally liable for all of the obligations of the joint venture. The respective joint venture agreements provide that each joint venture partner indemnify the other party for any liabilities incurred by such joint venture in excess of its ratable portion of such liabilities. Thus, it is possible that the Company could be required to pay or perform obligations in excess of its share if the other joint venture partners fail or refuse to pay or perform their respective share of the obligations. As of December 31, 2017, the Company was not aware of circumstances that would reasonably lead to material future claims against it in connection with these arrangements. The Company has other investment arrangements, as discussed in Note 4 - Fair Value of Financial Instruments and Note 15 - Related Party Transactions. The Company may incur costs or provide financing, performance, financial and/or other guarantees to or in connection with these arrangements. Self-Insurance. MasTec maintains insurance policies for workers’ compensation, general liability and automobile liability, which are subject to per claim deductibles. The Company is self-insured up to the amount of the deductible. The Company also maintains excess umbrella coverage. As of December 31, 2017 and 2016, MasTec’s liability for unpaid claims and associated expenses, including incurred but not reported losses related to these policies, totaled $106.2 million and $85.8 million, respectively, of which $72.2 million and $55.2 million, respectively, were reflected within other long-term liabilities in the consolidated balance sheets. MasTec also maintains an insurance policy with respect to employee group medical claims, which is subject to annual per employee maximum losses. MasTec’s liability for employee group medical claims totaled $2.6 million as of both December 31, 2017 and 2016. The Company is required to post letters of credit and provide cash collateral to certain of its insurance carriers and to provide surety bonds in certain states. Insurance-related letters of credit for the Company’s workers’ compensation, general liability and automobile liability policies amounted to $88.9 million and $85.1 million as of December 31, 2017 and 2016, respectively. In addition, cash collateral deposited with insurance carriers, which is included within other long-term assets, amounted to $1.6 million and $1.5 million for these policies as of December 31, 2017 and 2016, respectively. Outstanding surety bonds related to workers’ compensation self-insurance programs amounted to $15.2 million and $13.5 million as of December 31, 2017 and 2016, respectively. Employment Agreements. The Company has employment agreements with certain executives and other employees, which provide for compensation and certain other benefits and for severance payments under certain circumstances. Certain employment agreements also contain clauses that become effective upon a change in control of the Company. Upon the occurrence of any of the defined events in the various employment agreements, the Company would be obligated to pay certain amounts to the relevant employees, which vary with the level of the employees’ respective responsibility. Collective Bargaining Agreements and Multiemployer Plans. As discussed in Note 1 - Business, Basis of Presentation and Significant Accounting Policies, certain of MasTec’s subsidiaries are party to various collective bargaining agreements with unions representing certain of their employees, which require the Company to pay specified wages, provide certain benefits to their union employees and contribute certain amounts to MEPPs. The Employee Retirement Income Security Act of 1974, as amended by the Multiemployer Pension Plan Amendments Act of 1980 (collectively, “ERISA”), which governs U.S.-registered multiemployer pension plans, subjects employers to substantial liabilities in the event of the employer’s complete or partial withdrawal from, or upon termination of, such plans. The Company currently contributes, and in the past has contributed to, plans that are underfunded, and, therefore, could have potential liability associated with a voluntary or involuntary withdrawal from, or termination of, these plans. In November 2014, the Company, along with other members of the Pipe Line Contractors Association (the “PLCA”), voluntarily terminated its participation in several MEPPs. Additionally, the Company, along with other members of the PLCA, voluntarily withdrew from the Central States Southeast and Southwest Areas Pension Fund (“Central States”) in 2011, for which the Company established and paid a $6.4 million withdrawal liability. During the year ended December 31, 2017, the Company recognized $0.7 million of expense in connection with the expected final settlement of this matter. The Company does not have plans to withdraw from, and is not aware of circumstances that would reasonably lead to material claims against it, in connection with its participation in any other plans. However, there can be no assurance that the Company will not be assessed liabilities in the future. Based upon the information available to the Company from plan administrators as of December 31, 2017, several of the MEPPs in which it participates are underfunded and, as a result, the Company could be required to increase its contributions, including in the form of a surcharge on future benefit contributions. The amount of additional funds the Company may be obligated to contribute in the future cannot be estimated, as these amounts are based on future levels of work of the union employees covered by these plans, investment returns and the level of underfunding of such plans. Indemnities. The Company generally indemnifies its customers for the services it provides under its contracts, as well as other specified liabilities, which may subject the Company to indemnity claims, liabilities and related litigation. As of December 31, 2017 and 2016, the Company was not aware of any material asserted or unasserted claims in connection with these indemnity obligations. Other Guarantees. In the ordinary course of its business, from time to time, MasTec guarantees the obligations of its subsidiaries, including obligations under certain contracts with customers, certain lease obligations and in some states, obligations in connection with obtaining contractors’ licenses. MasTec has also issued performance and other guarantees in connection with certain of its equity investments. MasTec also generally warrants the work it performs for a one to two year period following substantial completion of a project. Much of the work performed by the Company is evaluated for defects shortly after the work is completed. Accrued warranty claims are, and historically have been, de minimis. However, if warranty claims occur, the Company could be required to repair or replace warrantied items, or, if customers elect to repair or replace the warrantied item using the services of another provider, the Company could be required to pay for the cost of the repair or replacement. Concentrations of Risk. The Company is subject to certain risk factors, including, but not limited to: risks related to customer consolidation, rapid technological and regulatory changes; changes in customers’ capital spending plans; risks related to market conditions and/or economic downturns; competition; the ability to manage projects effectively and in accordance with management’s estimates; customer disputes related to the performance of services; the nature of its contracts, which do not obligate MasTec’s customers to undertake any infrastructure projects and may be canceled on short notice; seasonality, adverse weather conditions and fluctuations in operational factors; risks related to the Company’s acquisitions and investment arrangements, including acquisition integration and financing; recoverability of goodwill; governmental and/or regulatory changes or other factors affecting the industries in which the Company operates; potential exposure to environmental liabilities; collectibility of receivables; exposure from system or information technology interruptions; availability of qualified employees; the adequacy of our reserves; exposure to litigation; exposure related to foreign operations; and exposure to multiemployer pension plan liabilities. The Company grants credit, generally without collateral, to its customers. Consequently, the Company is subject to potential credit risk related to changes in business and economic factors. However, MasTec generally has certain lien rights on that work and maintains a diverse customer base. The Company believes its billing and collection policies are adequate to minimize potential credit risk. MasTec’s customers include: public and private energy providers; pipeline operators; wireless and wireline/fiber service providers; broadband operators; install-to-the-home service providers; and government entities. The industries served by MasTec’s customers include, among others: communications; and utilities (including petroleum and natural gas pipeline infrastructure; electrical utility transmission and distribution; power generation; heavy civil and industrial infrastructure). The Company had approximately 500 customers for the year ended December 31, 2017. As of December 31, 2017 and 2016, one customer accounted for approximately 46% and 24%, respectively, of the Company’s consolidated net accounts receivable position, which represents accounts receivable, net, less BIEC. As of December 31, 2017 and 2016, a separate customer accounted for approximately 15% and 17%, respectively, of the Company’s consolidated net accounts receivable position. In addition, the Company derived 78%, 76% and 61%, of its revenue from its top ten customers for the years ended December 31, 2017, 2016 and 2015, respectively.

Related Party Transactions	12 Months Ended
Related Party Transactions	Dec. 31, 2017
Related Party Transactions [Abstract]
Related Party Transactions	Note 15 - Related Party Transactions In connection with a 2017 acquisition, the Company acquired a 40% interest in an entity, which is valued at $0.4 million and is accounted for as an equity method investment. The Company has a subcontracting arrangement with this entity. For the year ended December 31, 2017, the Company incurred $0.2 million of expenses under this subcontracting arrangement, and there were no amounts outstanding as of December 31, 2017. For the year ended December 31, 2017, the Company advanced $0.3 million on behalf of this entity, net, which was outstanding as of December 31, 2017. The acquired business also had a vendor financing arrangement with an entity that was owned by a member of subsidiary management, which arrangement was completed in 2017. Payments made under this arrangement for the year ended December 31, 2017 totaled $5.3 million, and no amounts were outstanding as of December 31, 2017. MasTec purchases, rents and leases equipment used in its business from a number of different vendors on a non-exclusive basis, including CCI, in which the Company has a cost method investment. Juan Carlos Mas, who is the brother of Jorge Mas, Chairman of MasTec’s Board of Directors, and José R. Mas, MasTec’s Chief Executive Officer, serves as the chairman of CCI, and a member of management of a MasTec subsidiary is a minority owner. For the years ended December 31, 2017 and 2016, MasTec paid CCI approximately $54.9 million and $24.5 million, net of rebates, for equipment supplies, rentals, leases and servicing, and for the year ended December 31, 2015, paid approximately $10.6 million. As of December 31, 2017 and 2016, related payables totaled approximately $2.7 million and $1.5 million, respectively. MasTec entered into a subcontracting arrangement in 2016 with an entity for the performance of construction services, the minority owners of which include an entity controlled by Jorge Mas and José R. Mas, along with two members of management of a MasTec subsidiary. For the years ended December 31, 2017 and 2016, MasTec incurred $78.0 million and $12.9 million, respectively, of expenses under this subcontracting arrangement, and during 2016, sold equipment totaling $0.3 million to this entity. As of December 31, 2017 and 2016, related amounts payable totaled $2.0 million and $0.1 million, respectively. MasTec leases employees to a customer in which Jorge Mas and José R. Mas own a majority interest. For each of the years ended December 31, 2017, 2016 and 2015, MasTec charged approximately $0.8 million to this customer. As of both December 31, 2017 and 2016, outstanding receivables from employee leasing arrangements with this customer totaled $0.2 million. MasTec also provides satellite communication services to this customer. For the year ended December 31, 2017, revenue from satellite communication services provided to this customer totaled approximately $0.8 million and for each of the years ended December 31, 2016 and 2015, totaled approximately $0.9 million. As of December 31, 2017 and 2016, receivables totaled approximately $0.3 million and $0.4 million, respectively. MasTec leases a property located in Florida from Irma S. Mas, the mother of Jorge Mas and José R. Mas. For each of the years ended December 31, 2017, 2016 and 2015, lease payments associated with this property totaled approximately $48,000. MasTec entered into a leasing arrangement in 2015 with an independent third party that leases an aircraft from a Company owned by Jorge Mas. For the years ended December 31, 2017 and 2016, MasTec paid $2.0 million and $2.6 million, respectively, under this leasing arrangement. As of December 31, 2017 and 2016, related amounts payable were de minimis. Activity in 2015 was de minimis. For the years ended December 31, 2017, 2016 and 2015, related party lease payments to entities that are associated with members of subsidiary management for operational facilities and equipment totaled approximately $46.8 million, $43.3 million and $22.1 million, respectively. Payables associated with related party leases totaled approximately $0.1 million and $0.3 million as of December 31, 2017 and 2016, respectively. Additionally, payments to entities that are associated with members of subsidiary management for various types of supplies and services, including ancillary construction services, project-related site restoration and marketing and business development activities totaled approximately $63.9 million, $27.7 million and $10.5 million for the years ended December 31, 2017, 2016 and 2015, respectively. As of December 31, 2017 and 2016, related payables totaled approximately $5.2 million and $3.7 million, respectively. In addition, in 2017, MasTec entered into an arrangement to perform construction services for an entity, of which a member of subsidiary management is a minority owner. Revenue from this arrangement totaled $2.6 million for the year ended December 31, 2017, and related receivables totaled $0.6 million as of December 31, 2017. In 2017, MasTec acquired an oil and gas pipeline equipment company that was formerly owned by a member of subsidiary management for $40.6 million in cash and an estimated earn-out liability of $57.2 million. MasTec previously leased equipment from this company. In February 2018, MasTec acquired a construction management firm specializing in steel building systems, of which Juan Carlos Mas was a minority owner, for approximately $5 million in cash plus contingent earn-out consideration. For the years ended December 31, 2017, 2016 and 2015 revenue recognized by the Company’s Pacer subsidiary for work performed for a contractual joint venture in which it holds a 35% undivided interest totaled $1.5 million, $1.0 million and $2.1 million, respectively. As of December 31, 2017 and 2016, receivables, net of BIEC, from this contractual joint venture totaled $0.8 million and $0.7 million, respectively. Related performance guarantees, which are based on the original full contract value, as of both December 31, 2017 and 2016 totaled Canadian $132.1 million (or approximately $105.1 million and $98.3 million, respectively), which was approximately 90% complete as of December 31, 2017. In connection with this contractual joint venture, the Company provided project-related financing of $7.2 million and $6.8 million, respectively, for the years ended December 31, 2017 and 2016. As of December 31, 2017, there were no material amounts committed to this entity. Non-controlling interests in entities consolidated by the Company represent ownership interests held by members of management of certain of the Company’s subsidiaries, primarily in the Company’s Oil and Gas segment. During the years ended December 31, 2017 and 2016, the Company had a subcontracting arrangement with one of these entities for the performance of ancillary oil and gas construction services, which transactions were eliminated in consolidation. In October 2017, the Company acquired the remaining non-controlling interests of one of these entities for $21.4 million in cash and an earn-out liability of $9.0 million. During the year ended December 31, 2017, the Company made distributions of earnings of $1.3 million to holders of these non-controlling interests, and a remaining distribution of $0.6 million will be made to the former holders in the first quarter of 2018. Cash paid to acquire the remaining interests of this entity is included within payments to non-controlling interests in the consolidated statements of cash flows, and the earn-out liability is reflected within other current and other long-term liabilities, as appropriate, in the consolidated balance sheets. Split Dollar Agreements As of December 31, 2017, MasTec had a split dollar agreement with Jorge Mas, and José R. Mas and Juan Carlos Mas, as trustees of the Jorge Mas Irrevocable Trust, dated June 1, 2012 (the “Jorge Mas trust”), under which MasTec was the sole owner of the policies subject to the agreement. The Company made the premium payments under each of the policies. Upon the death of Jorge Mas or the survivor of Jorge Mas and his wife under the applicable policy, MasTec was entitled to receive a portion of the death benefit under the policy equal to the greater of (i) premiums paid by the Company on the policy and (ii) the then cash value of the policy (excluding surrender charges or other similar charges or reductions) immediately before the triggering death. The balance of the death benefit was payable to the Jorge Mas trust or other beneficiary designated by the trustees. In the event of the Company’s bankruptcy or dissolution, the Jorge Mas trust had the assignable option to purchase the policies subject to the split dollar agreement from the Company. The purchase price for each policy was the greater of either the total premiums paid by the Company for the policy, or the then cash value of the policy, excluding surrender charges or other similar charges or reductions. The total maximum face amount of the insurance policies subject to the split dollar agreement was capped at $200 million. The Company was designated as the named fiduciary under the split dollar agreement, and the policy could not have been surrendered without the express written consent of the Jorge Mas trust. In addition, as of December 31, 2017, MasTec had a split dollar agreement with José R. Mas, and Jorge Mas, Juan Carlos Mas and Patricia Mas, as trustees of the José Ramon Mas Irrevocable Trust, dated December 7, 2012 (the “José R. Mas trust”), under which MasTec was the sole owner of each of the policies subject to the agreement. The Company made the premium payments under each of the policies. Upon the death of José R. Mas or the survivor of José R. Mas and his wife under the applicable policy, MasTec was entitled to receive a portion of the death benefit under the policy equal to the greater of (i) premiums paid by the Company on the policy and (ii) the then cash value of the policy (excluding surrender charges or other similar charges or reductions) immediately before the triggering death. The balance of the death benefit was payable to the José R. Mas trust or other beneficiary designated by the trustees. In the event of the Company’s bankruptcy or dissolution, the José R. Mas trust had the assignable option to purchase the policies subject to the split dollar agreement from the Company. The purchase price for each policy was the greater of either the total premiums paid by the Company for the policy, or the then cash value of the policy, excluding surrender charges or other similar charges or reductions. The total maximum face amount of the insurance policies subject to the split dollar agreement was capped at $75 million. The Company was designated as the named fiduciary under the split dollar agreement, and the policy could not have been surrendered without the express written consent of the José R. Mas trust. In connection with the split dollar agreement for Jorge Mas, the Company paid approximately $1.1 million in each of the years ended December 31, 2017, 2016 and 2015. In connection with the split dollar agreement for José R. Mas, the Company paid approximately $0.7 million in each of the years ended December 31, 2017, 2016 and 2015. As of December 31, 2017 and 2016, life insurance assets associated with these agreements, which amounts are included within other long-term assets, totaled $16.6 million and $14.8 million, respectively. In February 2018, Jorge Mas, the Company and José R. Mas and Juan Carlos Mas, as trustees of the Jorge Mas trust, entered into an amended and restated split dollar life insurance agreement that replaces the prior split dollar agreement with Jorge Mas. Additionally, in February 2018, José R. Mas, the Company and Jorge Mas, Juan Carlos Mas and Patricia Mas, as trustees of the José R. Mas trust, entered into an amended and restated split dollar life insurance agreement that replaces the prior split dollar life insurance agreement with José R. Mas. Details of the amended and restated split dollar life insurance agreements with each of Jorge and José R. Mas (each a “Covered Executive”) are summarized below. The Company is the sole owner of each of the policies subject to the applicable amended and restated split dollar agreement. The Company makes the premium payments under each of the policies. Upon the death of the applicable Covered Executive or the survivor thereof and his wife under the applicable policy, the Company is entitled to receive a portion of the death benefit under the policy equal to the greater of (i) premiums paid by the Company on the policy and (ii) the then cash value of the policy (excluding surrender charges or other similar charges or reductions) immediately before the triggering death. The balance of the death benefit is payable to the Jorge Mas trust or the José R. Mas trust, as applicable, or other beneficiary designated by the applicable trustees. In the event of (i) the Company’s bankruptcy or dissolution that does not qualify as a “change in control” of the Company, (ii) the death of the applicable Covered Executive, (iii) the death of the wife of the Covered Executive, or (iv) a “change in control” of the Company, the applicable trust shall have the assignable option to purchase the policies subject to the applicable split dollar agreement from the Company. The purchase price for each policy shall be the greatest of (i) the total premiums paid by the Company for the policy, (ii) the then cash value of the policy, excluding surrender charges or other similar charges or reductions, or (iii) only in the case of any purchase that is not as a result of the first to occur of an event described in the foregoing clauses (ii) and (iv), the fair market value of the policy. The purchase price for each policy shall be payable in cash or a promissory note, if and to the extent that the Company determines that payment with a promissory note could not violate applicable law. In the event of a “change in control” of the Company, the Company shall make all the then unpaid premium payments under the policies subject to the split dollar agreements and any other payments to the insurer necessary to cause the policies subject to the split dollar agreements to be fully paid. In addition, if any policies subject to the split dollar agreements are purchased from the Company, the Company shall make all the then unpaid premium payments under the purchased policies and any other payments to the insurer necessary to cause the purchased policies to be fully paid. The total maximum face amount of the insurance policies subject to the split dollar agreements is capped at $200 million in the case of Jorge Mas and $75 million in the case of Jose R. Mas. The Company is designated as the named fiduciary under each split dollar agreement, and the policies subject to the split dollar agreement may not be surrendered without the express written consent of the applicable trust.

Quarterly Information (Unaudited)

12 Months Ended

Dec. 31, 2017

Quarterly Financial Information Disclosure [Abstract]

Quarterly Information (Unaudited)

Note 16 – Quarterly Information (Unaudited)

The following table presents selected unaudited quarterly operating results for the years ended December 31, 2017 and 2016 (in millions, except per share data). The Company believes that all necessary adjustments have been included in the amounts stated below to present fairly the quarterly results when read in conjunction with the consolidated financial statements and notes thereto. The sum of the individual quarterly amounts to the full year amounts as disclosed below may contain slight summation differences due to rounding.



	For the 2017 Quarters Ended								For the 2016 Quarters Ended
	March 31		June 30		September 30		December 31		March 31			June 30		September 30		December 31
Revenue	$	1,158.2	$	1,890.2	$	1,955.8	$	1,602.9	$	974.2		$	1,232.4	$	1,586.2	$	1,341.9
Costs of revenue, excluding depreciation and amortization	$	971.1	$	1,626.3	$	1,726.2	$	1,421.7	$	884.4		$	1,068.2	$	1,369.0	$	1,120.6
Net income (loss)	$	40.6	$	83.3	$	64.2	$	160.7	$	(2.9	)	$	24.4	$	56.5	$	55.9
Net income (loss) attributable to MasTec, Inc.	$	41.0	$	81.7	$	63.8	$	160.8	$	(2.7	)	$	24.1	$	56.3	$	53.6
Earnings (loss) per share:
Basic	$	0.51	$	1.01	$	0.79	$	1.98	$	(0.03	)	$	0.30	$	0.70	$	0.67
Diluted	$	0.50	$	0.99	$	0.77	$	1.95	$	(0.03	)	$	0.30	$	0.69	$	0.66

Certain transactions affecting comparisons of the Company’s quarterly results, which may not represent the amounts recognized for the full year for such transactions, include the following:


(i)	Project losses on a proportionately consolidated non-controlled Canadian joint venture, pretax, totaling $7.0 million in the first quarter of 2017, respectively, and totaling $5.1 million in the third quarter of 2016;


(ii)	Excess tax benefits from share-based compensation of $5.6 million in the fourth quarter of 2017;


(iii)	An income tax benefit of $120.1 million from tax reform legislation in the fourth quarter of 2017;


(iv)	Restructuring charges, pretax, totaling $4.1 million, $5.1 million, $4.7 million and $1.4 million in the first, second, third, and fourth quarters of 2016, respectively.

Supplemental Guarantor Financial Information

12 Months Ended

Dec. 31, 2017

Condensed Financial Statements, Supplemental Guarantor Information [Abstract]

Supplemental Guarantor Financial Information

Note 17 – Supplemental Guarantor Condensed Consolidating Financial Information

The 4.875% Senior Notes are fully and unconditionally guaranteed on an unsecured, unsubordinated, joint and several basis by certain of the Company’s existing and future 100%-owned direct and indirect domestic subsidiaries that are, as of December 31, 2017, each guarantors of the Credit Facility or other outstanding indebtedness (the “Guarantor Subsidiaries”). The Company’s subsidiaries organized outside of the United States and certain domestic subsidiaries (collectively, the “Non-Guarantor Subsidiaries”) do not guarantee these notes. A Guarantor Subsidiary’s guarantee is subject to release in certain customary circumstances, including upon the sale of a majority of the capital stock or substantially all of the assets of such Guarantor Subsidiary; if the Guarantor Subsidiary’s guarantee under the Company’s Credit Facility and other indebtedness is released or discharged (other than due to payment under such guarantee); or when the requirements for legal defeasance are satisfied or the obligations are discharged in accordance with the related indentures.

The following supplemental financial information sets forth the condensed consolidating balance sheets and the condensed consolidating statements of operations and comprehensive income (loss) and cash flows for MasTec, Inc., the Guarantor Subsidiaries on a combined basis, the Non-Guarantor Subsidiaries on a combined basis and the eliminations necessary to arrive at the information for the Company as reported on a consolidated basis. Eliminations represent adjustments to eliminate investments in subsidiaries and intercompany balances and transactions between or among MasTec, Inc., the Guarantor Subsidiaries and the Non-Guarantor Subsidiaries. Investments in subsidiaries are accounted for using the equity method for this presentation.

CONDENSED CONSOLIDATING STATEMENTS OF OPERATIONS AND COMPREHENSIVE INCOME (LOSS) (in millions)



For the Year Ended December 31, 2017	MasTec, Inc.			Guarantor Subsidiaries			Non-Guarantor Subsidiaries			Eliminations			Consolidated MasTec, Inc.
Revenue	$	—		$	6,222.3		$	457.0		$	(72.3	)	$	6,607.0
Costs of revenue, excluding depreciation and amortization	—			5,378.6			439.0			(72.3		)	5,745.3
Depreciation and amortization	—			159.1			28.9			—			188.0
General and administrative expenses	2.3			256.3			16.5			—			275.1
Interest expense (income), net	—			123.6			(62.6		)	—			61.0
Equity in earnings of unconsolidated affiliates	—			—			(21.3		)	—			(21.3		)
Other income, net	—			(13.0		)	—			—			(13.0		)
(Loss) income before income taxes	$	(2.3	)	$	317.7		$	56.5		$	—		$	371.8
Benefit from (provision for) income taxes	0.2			(18.1		)	(5.0		)	—			(22.9		)
Net (loss) income before equity in income from subsidiaries	$	(2.1	)	$	299.6		$	51.5		$	—		$	348.9
Equity in income from subsidiaries, net of tax	349.3			—			—			(349.3		)	—
Net income (loss)	$	347.2		$	299.6		$	51.5		$	(349.3	)	$	348.9
Net income (loss) attributable to non-controlling interests	—			2.4			(0.7		)	—			1.7
Net income (loss) attributable to MasTec, Inc.	$	347.2		$	297.2		$	52.2		$	(349.3	)	$	347.2
Comprehensive income (loss)	$	349.3		$	299.6		$	53.6		$	(351.4	)	$	351.0

CONDENSED CONSOLIDATING STATEMENTS OF OPERATIONS AND COMPREHENSIVE INCOME (LOSS) (in millions)



For the Year Ended December 31, 2016	MasTec, Inc.			Guarantor Subsidiaries			Non-Guarantor Subsidiaries			Eliminations			Consolidated MasTec, Inc.
Revenue	$	—		$	4,790.9		$	353.8		$	(10.0	)	$	5,134.7
Costs of revenue, excluding depreciation and amortization	—			4,101.2			350.9			(10.0		)	4,442.1
Depreciation and amortization	—			134.2			30.7			—			164.9
General and administrative expenses	2.4			234.4			24.6			—			261.4
Interest expense (income), net	—			112.0			(61.3		)	—			50.7
Equity in earnings of unconsolidated affiliates	—			—			(3.5		)	—			(3.5		)
Other income, net	—			—			(6.8		)	—			(6.8		)
(Loss) income before income taxes	$	(2.4	)	$	209.1		$	19.2		$	—		$	225.8
Benefit from (provision for) income taxes	0.9			(72.6		)	(20.1		)	—			(91.8		)
Net (loss) income before equity in income from subsidiaries	$	(1.5	)	$	136.5		$	(0.9	)	$	—		$	134.0
Equity in income from subsidiaries, net of tax	132.8			—			—			(132.8		)	—
Net income (loss)	$	131.3		$	136.5		$	(0.9	)	$	(132.8	)	$	134.0
Net income (loss) attributable to non-controlling interests	—			3.3			(0.5		)	—			2.8
Net income (loss) attributable to MasTec, Inc.	$	131.3		$	133.2		$	(0.4	)	$	(132.8	)	$	131.3
Comprehensive income (loss)	$	137.8		$	136.5		$	5.6		$	(139.3	)	$	140.6



For the Year Ended December 31, 2015	MasTec, Inc.			Guarantor Subsidiaries			Non-Guarantor Subsidiaries			Eliminations			Consolidated MasTec, Inc.
Revenue	$	—		$	3,527.0		$	689.7		$	(8.4	)	$	4,208.3
Costs of revenue, excluding depreciation and amortization	—			3,073.6			656.1			(8.4		)	3,721.3
Depreciation and amortization	—			130.6			39.1			—			169.7
Goodwill and intangible asset impairment	—			—			78.6			—			78.6
General and administrative expenses	2.1			235.4			28.4			—			265.9
Interest expense (income), net	—			111.0			(62.9		)	—			48.1
Equity in losses of unconsolidated affiliates	—			—			8.0			—			8.0
Other income, net	—			(6.2		)	(9.3		)	—			(15.5		)
Loss before income taxes	$	(2.1	)	$	(17.4	)	$	(48.3	)	$	—		$	(67.7	)
Benefit from (provision for) income taxes	1.1			9.3			(22.3		)	—			(12.0		)
Net loss before equity in losses from subsidiaries	$	(1.0	)	$	(8.1	)	$	(70.6	)	$	—		$	(79.7	)
Equity in losses from subsidiaries, net of tax	(78.1		)	—			—			78.1			—
Net (loss) income	$	(79.1	)	$	(8.1	)	$	(70.6	)	$	78.1		$	(79.7	)
Net loss attributable to non-controlling interests	—			—			(0.6		)	—			(0.6		)
Net (loss) income attributable to MasTec, Inc.	$	(79.1	)	$	(8.1	)	$	(70.0	)	$	78.1		$	(79.1	)
Comprehensive (loss) income	$	(117.5	)	$	(8.1	)	$	(109.0	)	$	116.5		$	(118.1	)

CONDENSED CONSOLIDATING BALANCE SHEETS (in millions)



As of December 31, 2017	MasTec, Inc.		Guarantor Subsidiaries		Non-Guarantor Subsidiaries		Eliminations			Consolidated MasTec, Inc.
Assets
Total current assets	$	—	$	1,536.6	$	332.9	$	(17.1	)	$	1,852.4
Property and equipment, net	—		638.7		67.8		—			706.5
Goodwill and other intangible assets, net	—		1,187.9		141.0		—			1,328.9
Investments in and advances to consolidated affiliates, net	1,415.0		847.7		746.6		(3,009.3		)	—
Other long-term assets	15.8		23.4		139.6		—			178.8
Total assets	$	1,430.8	$	4,234.3	$	1,427.9	$	(3,026.4	)	$	4,066.6
Liabilities and equity
Total current liabilities	$	—	$	778.6	$	202.3	$	(17.1	)	$	963.8
Long-term debt	—		1,269.4		11.3		—			1,280.7
Other long-term liabilities	—		379.9		8.8		—			388.7
Total liabilities	$	—	$	2,427.9	$	222.4	$	(17.1	)	$	2,633.2
Total equity	$	1,430.8	$	1,806.4	$	1,205.5	$	(3,009.3	)	$	1,433.4
Total liabilities and equity	$	1,430.8	$	4,234.3	$	1,427.9	$	(3,026.4	)	$	4,066.6



As of December 31, 2016	MasTec, Inc.		Guarantor Subsidiaries		Non-Guarantor Subsidiaries		Eliminations			Consolidated MasTec, Inc.
Assets
Total current assets	$	—	$	1,257.2	$	155.5	$	(10.2	)	$	1,402.5
Property and equipment, net	—		463.7		85.4		—			549.1
Goodwill and other intangible assets, net	—		1,037.4		138.2		—			1,175.6
Investments in and advances to consolidated affiliates, net	1,083.9		617.4		867.7		(2,569.0		)	—
Other long-term assets	12.6		25.2		18.1		—			55.9
Total assets	$	1,096.5	$	3,400.9	$	1,264.9	$	(2,579.2	)	$	3,183.1
Liabilities and equity
Total current liabilities	$	—	$	742.8	$	107.4	$	(10.2	)	$	840.0
Long-term debt	—		941.7		19.7		—			961.4
Other long-term liabilities	—		258.1		20.0		—			278.1
Total liabilities	$	—	$	1,942.6	$	147.1	$	(10.2	)	$	2,079.5
Total equity	$	1,096.5	$	1,458.3	$	1,117.8	$	(2,569.0	)	$	1,103.6
Total liabilities and equity	$	1,096.5	$	3,400.9	$	1,264.9	$	(2,579.2	)	$	3,183.1

CONDENSED CONSOLIDATING STATEMENTS OF CASH FLOWS (in millions)



For the Year Ended December 31, 2017	MasTec, Inc.			Guarantor Subsidiaries			Non-Guarantor Subsidiaries			Eliminations		Consolidated MasTec, Inc.
Net cash provided by operating activities	$	—		$	155.1		$	1.2		$	—	$	156.3
Cash flows from investing activities:
Cash paid for acquisitions, net of cash acquired	—			(116.0		)	—			—		(116.0		)
Capital expenditures	—			(120.1		)	(3.3		)	—		(123.4		)
Proceeds from sale of property and equipment	—			18.2			1.8			—		20.0
Payments for other investments	—			(3.8		)	(73.3		)	—		(77.1		)
Proceeds from other investments	—			1.2			22.6			—		23.8
Net cash used in investing activities	$	—		$	(220.5	)	$	(52.2	)	$	—	$	(272.7	)
Cash flows from financing activities:
Proceeds from credit facilities	—			2,674.4			24.6			—		2,699.0
Repayments of credit facilities	—			(2,428.9		)	(28.4		)	—		(2,457.3		)
Repayments of other borrowings and capital lease obligations, net	—			(61.5		)	(9.6		)	—		(71.1		)
Payments of acquisition-related contingent consideration	—			(18.8		)	—			—		(18.8		)
Payments to non-controlling interests, including acquisition of interests and distributions	—			(22.7		)	—			—		(22.7		)
Payments for stock-based awards, net	(3.1		)	—			—			—		(3.1		)
Repurchase of common stock	(1.6		)	—			—			—		(1.6		)
Other financing activities, net	—			(6.3		)	—			—		(6.3		)
Net financing activities and advances from (to) consolidated affiliates	4.7			(89.6		)	84.9			—		—
Net cash provided by financing activities	$	—		$	46.6		$	71.5		$	—	$	118.2
Effect of currency translation on cash	—			—			(0.1		)	—		(0.1		)
Net (decrease) increase in cash and cash equivalents	$	—		$	(18.8	)	$	20.4		$	—	$	1.6
Cash and cash equivalents - beginning of period	—			28.9			9.9			—		38.8
Cash and cash equivalents - end of period	$	—		$	10.1		$	30.3		$	—	$	40.3



For the Year Ended December 31, 2016	MasTec, Inc.			Guarantor Subsidiaries			Non-Guarantor Subsidiaries			Eliminations		Consolidated MasTec, Inc.
Net cash provided by operating activities	$	—		$	130.5		$	75.1		$	—	$	205.6
Cash flows from investing activities:
Cash paid for acquisitions, net of cash acquired	—			(4.1		)	—			—		(4.1		)
Capital expenditures	—			(112.6		)	(4.5		)	—		(117.1		)
Proceeds from sale of property and equipment	—			7.6			3.6			—		11.2
Payments for other investments	—			(3.9		)	(28.2		)	—		(32.2		)
Proceeds from other investments	—			—			1.1			—		1.1
Net cash used in investing activities	$	—		$	(113.0	)	$	(28.0	)	$	—	$	(141.0	)
Cash flows from financing activities:
Proceeds from credit facilities	—			1,553.4			128.0			—		1,681.4
Repayments of credit facilities	—			(1,496.6		)	(130.5		)	—		(1,627.1		)
Repayments of other borrowings and capital lease obligations, net	—			(50.4		)	(18.3		)	—		(68.7		)
Payments of acquisition-related contingent consideration	—			(16.6		)	(3.2		)	—		(19.8		)
Proceeds from stock-based awards, net	4.2			—			—			—		4.2
Other financing activities, net	0.1			0.4			—			—		0.5
Net financing activities and advances (to) from consolidated affiliates	(4.3		)	16.4			(12.1		)	—		—
Net cash provided by (used in) financing activities	$	—		$	6.6		$	(36.1	)	$	—	$	(29.5	)
Effect of currency translation on cash	—			—			(1.3		)	—		(1.3		)
Net increase in cash and cash equivalents	$	—		$	24.1		$	9.7		$	—	$	33.8
Cash and cash equivalents - beginning of period	—			4.8			0.2			—		5.0
Cash and cash equivalents - end of period	$	—		$	28.9		$	9.9		$	—	$	38.8

CONDENSED CONSOLIDATING STATEMENTS OF CASH FLOWS (in millions)



For the Year Ended December 31, 2015	MasTec, Inc.			Guarantor Subsidiaries			Non-Guarantor Subsidiaries			Eliminations		Consolidated MasTec, Inc.
Net cash provided by operating activities	$	0.9		$	358.5		$	8.0		$	—	$	367.4
Cash flows from investing activities:
Cash paid for acquisitions, net of cash acquired	—			(0.1		)	—			—		(0.1		)
Capital expenditures	—			(71.9		)	(12.5		)	—		(84.4		)
Proceeds from sale of property and equipment	—			10.5			3.4			—		13.9
Payments for other investments	(1.9		)	—			(125.6		)	—		(127.5		)
Proceeds from other investments	—			—			69.4			—		69.4
Net cash used in investing activities	$	(1.9	)	$	(61.5	)	$	(65.3	)	$	—	$	(128.7	)
Cash flows from financing activities:
Proceeds from credit facilities	—			1,097.3			605.1			—		1,702.4
Repayments of credit facilities	—			(1,154.3		)	(587.8		)	—		(1,742.1		)
Repayments of other borrowings and capital lease obligations, net	—			(54.3		)	(16.6		)	—		(70.9		)
Repurchase of common stock	(100.0		)	—			—			—		(100.0		)
Payments of acquisition-related contingent consideration	—			(37.3		)	(10.2		)	—		(47.5		)
Proceeds from (payments for) stock-based awards, net	2.7			(1.1		)	—			—		1.6
Other financing activities, net	—			(2.4		)	—			—		(2.4		)
Net financing activities and advances from (to) consolidated affiliates	98.3			(158.6		)	60.3			—		—
Net cash provided by (used in) financing activities	$	1.0		$	(310.7	)	$	50.8		$	—	$	(258.9	)
Effect of currency translation on cash	—			—			1.1			—		1.1
Net decrease in cash and cash equivalents	$	—		$	(13.7	)	$	(5.4	)	$	—	$	(19.1	)
Cash and cash equivalents - beginning of period	—			18.5			5.6			—		24.1
Cash and cash equivalents - end of period	$	—		$	4.8		$	0.2		$	—	$	5.0

Schedule II - Valuation and Qualifying Accounts

12 Months Ended

Dec. 31, 2017

Valuation and Qualifying Accounts [Abstract]

Schedule II - Valuation and Qualifying Accounts

SCHEDULE II – VALUATION AND QUALIFYING ACCOUNTS

(in millions)



			Additions
	Balance at Beginning of Period		Charges to Cost and Expense			Other Additions			(Deductions)				Balance at End of Period
Year ended December 31, 2017
Allowance for doubtful accounts	$	8.4	$	2.6	^(a)	$	—		$	(2.8	)	^(b)	$	8.2
Costs and earnings in excess of billings allowance	9.5		22.3		^(a)	—			(4.6		)	^(b)	27.2
Inventory valuation reserve	3.5		6.2		^(c)	—			(2.0		)	^(d)	7.7
Valuation allowance for deferred tax assets	21.4		19.1		^(e)	—			—				40.5
Total	$	42.8	$	50.2		$	—		$	(9.4	)		$	83.6
Year ended December 31, 2016
Allowance for doubtful accounts	$	7.7	$	2.9	^(a)	$	—		$	(2.2	)	^(b)	$	8.4
Costs and earnings in excess of billings allowance	6.9		9.9		^(a)	—			(7.3		)	^(b)	9.5
Inventory valuation reserve	2.8		2.0		^(c)	—			(1.3		)	^(d)	3.5
Valuation allowance for deferred tax assets	10.6		9.8		^(e)	1.0		^(f)	—				21.4
Total	$	28.0	$	24.6		$	1.0		$	(10.8	)		$	42.8
Year ended December 31, 2015
Allowance for doubtful accounts	$	13.9	$	2.1	^(a)	$	—		$	(8.3	)	^(b)	$	7.7
Costs and earnings in excess of billings allowance	12.5		—		^(a)	—			(5.6		)	^(b)	6.9
Inventory valuation reserve	6.4		—		^(c)	—			(3.6		)	^(d)	2.8
Valuation allowance for deferred tax assets	0.2		0.1		^(e)	10.3		^(f)	—				10.6
Total	$	33.0	$	2.2		$	10.3		$	(17.5	)		$	28.0


(a)	Provisions for doubtful accounts and costs and earnings in excess of billings.


(b)	Write-offs and reversals of uncollectible accounts receivable and non-billable costs and earnings in excess of billings.


(c)	Provision for inventory obsolescence.


(d)	Inventory write-offs.


(e)	Additions related to federal, foreign, and state attributes.


(f)	Additions related to unrealized gains and losses.

Business, Basis of Presentation and Significant Accounting Policies (Policies)	12 Months Ended
	Dec. 31, 2017
Accounting Policies [Abstract]
Principles of Consolidation	Principles of Consolidation The accompanying consolidated financial statements include MasTec, Inc. and its subsidiaries and include the accounts of all majority owned subsidiaries over which the Company exercises control and, when applicable, entities in which the Company has a controlling financial interest. All significant intercompany balances and transactions have been eliminated in consolidation. Other parties’ interests in entities that MasTec consolidates are reported as non-controlling interests within equity. Net income or loss attributable to non-controlling interests is reported as a separate line item below net income or loss. The Company’s investments in entities for which the Company does not have a controlling interest, but for which it has the ability to exert significant influence, are accounted for using the equity method of accounting. Equity method investments are recorded as other long-term assets. Income or loss from these investments is recorded as a separate line item in the statements of operations. Intercompany profits or losses associated with the Company’s equity method investments are eliminated until realized by the investee in transactions with third parties. For equity investees in which the Company has an undivided interest in the assets, liabilities and profits or losses of an unincorporated entity, but the Company does not exercise control over the entity, the Company consolidates its proportional interest in the accounts of the entity. The cost method is used for investments in entities for which the Company does not have the ability to exert significant influence. Certain prior year amounts have been reclassified to conform to the current period presentation. Management determines whether each business entity in which it has equity interests, debt, or other investments constitutes a variable interest entity (“VIE”) based on the nature and characteristics of such arrangements. If an investment arrangement is determined to be a VIE, then management determines if the Company is the VIE’s primary beneficiary by evaluating several factors, including the Company’s: (i) risks and responsibilities; (ii) ownership interests; (iii) decision making powers; and (iv) financial interests, among other factors. If management determines the Company is the primary beneficiary of a VIE, then it would be consolidated, and other parties’ interests in the VIE would be accounted for as non-controlling interests. The primary beneficiary consolidating the VIE must normally have both (i) the power to direct the primary activities of the VIE and (ii) the obligation to absorb losses of the VIE or the right to receive benefits from the VIE, which, in either case, could be significant to the VIE. As of December 31, 2017, the Company determined that certain of its investment arrangements were VIEs; however, because it does not have the power to direct the primary activities that most significantly impact the economic performance of these VIEs, the Company is not the primary beneficiary, and accordingly, has not consolidated these VIEs.
Equity Method Investments	The Company’s investments in entities for which the Company does not have a controlling interest, but for which it has the ability to exert significant influence, are accounted for using the equity method of accounting. Equity method investments are recorded as other long-term assets. Income or loss from these investments is recorded as a separate line item in the statements of operations. Intercompany profits or losses associated with the Company’s equity method investments are eliminated until realized by the investee in transactions with third parties.
Unicorporated Entities, Proportional Consolidation	For equity investees in which the Company has an undivided interest in the assets, liabilities and profits or losses of an unincorporated entity, but the Company does not exercise control over the entity, the Company consolidates its proportional interest in the accounts of the entity.
Cost Method Investments	The cost method is used for investments in entities for which the Company does not have the ability to exert significant influence.
Reclassifications	Certain prior year amounts have been reclassified to conform to the current period presentation.
Variable Interest Entities	Management determines whether each business entity in which it has equity interests, debt, or other investments constitutes a variable interest entity (“VIE”) based on the nature and characteristics of such arrangements. If an investment arrangement is determined to be a VIE, then management determines if the Company is the VIE’s primary beneficiary by evaluating several factors, including the Company’s: (i) risks and responsibilities; (ii) ownership interests; (iii) decision making powers; and (iv) financial interests, among other factors. If management determines the Company is the primary beneficiary of a VIE, then it would be consolidated, and other parties’ interests in the VIE would be accounted for as non-controlling interests. The primary beneficiary consolidating the VIE must normally have both (i) the power to direct the primary activities of the VIE and (ii) the obligation to absorb losses of the VIE or the right to receive benefits from the VIE, which, in either case, could be significant to the VIE. As of December 31, 2017, the Company determined that certain of its investment arrangements were VIEs; however, because it does not have the power to direct the primary activities that most significantly impact the economic performance of these VIEs, the Company is not the primary beneficiary, and accordingly, has not consolidated these VIEs.
Translation of Foreign Currencies	Translation of Foreign Currencies The assets and liabilities of foreign subsidiaries with a functional currency other than the U.S. dollar are translated into U.S. dollars at period-end exchange rates, with resulting translation gains or losses accumulated within other comprehensive income or loss. Revenue and expenses are translated into U.S. dollars at average rates of exchange during the applicable period. Substantially all of the Company’s foreign operations use their local currency as their functional currency. Currency gains or losses resulting from transactions executed in currencies other than the functional currency are included in other income or expense, net.
Management Estimates	Management Estimates The preparation of consolidated financial statements in accordance with U.S. GAAP requires the use of estimates and assumptions that affect the amounts reported in the consolidated financial statements and accompanying notes. These estimates are based on historical experience and various other assumptions, the results of which form the basis of making judgments about the Company’s operating results and the carrying values of assets and liabilities that are not readily apparent from other sources. Key estimates include: the recognition of revenue and project profit or loss, which the Company defines as project revenue, less project costs of revenue, including project-related depreciation, in particular, on construction contracts accounted for under the percentage-of-completion method, for which the recorded amounts require estimates of costs to complete and the amount of probable contract price adjustments; allowances for doubtful accounts; fair value estimates, including those related to business acquisitions, valuations of goodwill and intangible assets, acquisition-related contingent consideration and equity investments; asset lives used in computing depreciation and amortization; fair values of financial instruments; self-insurance liabilities; other accruals and allowances; income taxes; and the estimated effects of litigation and other contingencies. While management believes that such estimates are reasonable when considered in conjunction with the Company’s consolidated financial position and results of operations taken as a whole, actual results could differ materially from those estimates.
Revenue Recognition	Revenue Recognition Revenue is derived from construction projects performed under master and other service agreements as well as from contracts for specific projects or jobs requiring the construction and installation of an entire infrastructure system or specified units within an entire infrastructure system. The Company frequently provides services under unit price or fixed price master service or other service agreements. Revenue and related costs for master and other service agreements billed on a time and materials basis are recognized as the services are rendered. Revenue derived from projects performed under master service and other service agreements totaled 36%, 43% and 48% of consolidated revenue for the years ended December 31, 2017, 2016 and 2015, respectively. The Company also performs services under master and other service agreements on a fixed fee basis, under which MasTec furnishes specified units of service for a fixed price per unit of service and revenue is recognized as the services are rendered. Revenue from fixed price contracts provides for a fixed amount of revenue for the entire project, subject to certain additions for changed scope or specifications. Revenue from these contracts, as well as for certain projects pursuant to master and other service agreements, is recognized using the percentage-of-completion method, under which the percentage of revenue to be recognized for a given project is measured by the percentage of costs incurred to date on the contract to the total estimated costs for the contract. Such contracts provide that the customer accept completion of progress to date and compensate the Company for services rendered, which may be measured in terms of costs incurred, units installed, hours expended or some other measure of progress. Contract costs include all direct materials, labor and subcontracted costs and those indirect costs related to contract performance, such as indirect labor, supplies, tools, repairs and the operational costs of capital equipment. Much of the materials associated with the Company’s work are customer-furnished and are therefore not included in contract revenue and costs. The estimation process for revenue recognized under the percentage-of-completion method is based on the professional knowledge and experience of the Company’s project managers, engineers and financial professionals. Management reviews estimates of contract revenue and costs on an ongoing basis. Changes in job performance, job conditions and management’s assessment of expected contract settlements are factors that influence estimates of total contract value and total costs to complete those contracts and, therefore, the Company’s profit recognition. Changes in these factors may result in revisions to costs and income, and their effects are recognized in the period in which the revisions are determined, which could materially affect the Company’s results of operations in the period in which such changes are recognized. For both the years ended December 31, 2017 and 2016, project profit was affected by less than 5% as a result of changes in contract estimates included in projects that were in process as of December 31, 2016 and 2015, respectively. Provisions for losses on uncompleted contracts are made in the period in which such losses are determined to be probable and the amount can be reasonably estimated. The majority of fixed price contracts are completed within one year. The Company may incur costs subject to change orders, whether approved or unapproved by the customer, and/or claims related to certain contracts. Management determines the probability that such costs will be recovered based upon engineering studies and legal opinions, past practices with the customer, specific discussions, correspondence or preliminary negotiations with the customer. The Company treats such costs as a cost of contract performance in the period incurred if it is not probable that the costs will be recovered, and defers costs or recognizes revenue up to the amount of the related cost if it is probable that the contract price will be adjusted and can be reliably estimated. As of December 31, 2017 and 2016, the Company had approximately $146 million and $17 million, respectively, of change orders and/or claims that had been included as contract price adjustments on certain contracts that were in the process of being resolved in the normal course of business, including through negotiation, arbitration and other proceedings. These contract price adjustments, which are included within costs and earnings in excess of billings or billed accounts receivable, as appropriate, represent management’s best estimate of contract revenue that has been earned and that management believes is probable of collection. As of both December 31, 2017 and 2016, these change orders were primarily related to contracts in the Oil and Gas segment. Revenue related to unapproved change orders totaled approximately $142 million and $4 million, respectively, for the years ended December 31, 2017 and 2016. The Company actively engages in substantive meetings with its customers to complete the final approval process, and generally expects these processes to be completed within one year. The amounts ultimately realized upon final acceptance by its customers could be higher or lower than such estimated amounts. Billings In Excess of Costs and Earnings (“BIEC”) on uncompleted contracts is classified within current liabilities. Costs and Earnings In Excess of Billings (“CIEB”), which is also referred to as work in process, is classified within current assets. Work in process on contracts is based on work performed but not yet billed to customers as per individual contract terms.
Revenue Recognition, Percentage-of-Completion Method	Revenue from fixed price contracts provides for a fixed amount of revenue for the entire project, subject to certain additions for changed scope or specifications. Revenue from these contracts, as well as for certain projects pursuant to master and other service agreements, is recognized using the percentage-of-completion method, under which the percentage of revenue to be recognized for a given project is measured by the percentage of costs incurred to date on the contract to the total estimated costs for the contract. Such contracts provide that the customer accept completion of progress to date and compensate the Company for services rendered, which may be measured in terms of costs incurred, units installed, hours expended or some other measure of progress. Contract costs include all direct materials, labor and subcontracted costs and those indirect costs related to contract performance, such as indirect labor, supplies, tools, repairs and the operational costs of capital equipment. Much of the materials associated with the Company’s work are customer-furnished and are therefore not included in contract revenue and costs. The estimation process for revenue recognized under the percentage-of-completion method is based on the professional knowledge and experience of the Company’s project managers, engineers and financial professionals. Management reviews estimates of contract revenue and costs on an ongoing basis. Changes in job performance, job conditions and management’s assessment of expected contract settlements are factors that influence estimates of total contract value and total costs to complete those contracts and, therefore, the Company’s profit recognition. Changes in these factors may result in revisions to costs and income, and their effects are recognized in the period in which the revisions are determined, which could materially affect the Company’s results of operations in the period in which such changes are recognized. For both the years ended December 31, 2017 and 2016, project profit was affected by less than 5% as a result of changes in contract estimates included in projects that were in process as of December 31, 2016 and 2015, respectively. Provisions for losses on uncompleted contracts are made in the period in which such losses are determined to be probable and the amount can be reasonably estimated. The majority of fixed price contracts are completed within one year.
Allowance for Doubtful Accounts	Allowance for Doubtful Accounts The Company maintains an allowance for doubtful accounts for estimated losses resulting from the inability of its customers to make required payments. Management analyzes the collectibility of trade accounts receivable and the adequacy of the allowance for doubtful accounts on a regular basis taking into consideration the aging of account balances, historical bad debt experience, customer concentrations, customer credit-worthiness, customer financial condition and credit reports, availability of mechanics’ and other liens, existence of payment bonds and other sources of payment and the current economic environment. The Company establishes an allowance for doubtful accounts for anticipated losses of its business units when a business unit has historical experience of losses that are considered to be ordinary course. In addition, an allowance is established when it is probable that a specific receivable is not collectible and the loss can be reasonably estimated. Amounts are written off against the allowance when they are considered to be uncollectible. If estimates of the collectibility of accounts receivable change, or should customers experience unanticipated financial difficulties, or if anticipated recoveries in existing bankruptcies or other work-out situations fail to materialize, additional allowances may be required. Estimates of collectibility are subject to significant change during times of economic weakness or uncertainty in either the overall economy or within the industries served by MasTec. Management actively monitors the economic environment and its impact on MasTec’s customers in connection with its evaluation of the Company’s accounts receivable portfolio and the adequacy of its allowance for doubtful accounts.
Cash and Cash Equivalents	Cash and Cash Equivalents Cash consisting of interest-bearing demand deposits is carried at cost, which approximates fair value. All highly liquid investments purchased with an original maturity of three months or less are considered to be cash equivalents, which are carried at fair value. On a daily basis, available funds are swept from the Company’s depository accounts into a concentration account and used to repay outstanding revolving loans under the Company’s senior secured credit facility. Cash balances maintained by certain operating subsidiaries and by entities that are proportionately consolidated that are not swept into the concentration account, as well as deposits made subsequent to the daily cash sweep, are classified as cash. Included in the Company’s cash balances as of December 31, 2017 and 2016 are amounts held by entities that are proportionately consolidated totaling $17.3 million and $7.7 million, respectively. These amounts are available to support the operations of those entities, but are not available for the Company’s other operations. The Company generally does not fund its disbursement accounts for checks it has written until the checks are presented to the bank for payment. Outstanding checks that have not yet cleared through the banking system represent book overdrafts, which are classified within accounts payable. There are no compensating balance requirements associated with the Company’s depository accounts and there are no other restrictions on the transfer of cash associated with the Company’s depository accounts.
Inventories	Inventories Inventories consist of materials and supplies for construction and installation projects, which are valued at the lower of cost or net realizable value using either the average cost or specific identification methods of costing. For materials or supplies purchased on behalf of specific customers or projects, loss of the customer or cancellation of the project could result in an impairment of the value of materials purchased. Technological or market changes can also render certain materials obsolete. Allowances for inventory obsolescence are determined based upon specific facts and circumstances and market conditions.
Property and Equipment	Property and equipment are recorded at cost, or, if acquired in a business combination, at the acquisition date fair value. Certain costs incurred in connection with developing or obtaining internal-use software are capitalized within office furniture and equipment. Depreciation and amortization of long-lived assets is computed using the straight-line method over the estimated useful lives of the respective assets. Leasehold improvements are depreciated over the shorter of the term of the lease or the estimated useful lives of the improvements. Property and equipment under capital leases are depreciated over their estimated useful lives. Expenditures for repairs and maintenance are charged to expense as incurred. Expenditures for betterments and major improvements are capitalized and depreciated over the remaining useful lives of the assets. The carrying amounts of assets sold or retired and the related accumulated depreciation are eliminated in the year of disposal, with resulting gains or losses included in other income or expense.
Finite-Lived Intangible Assets	Acquired intangible assets that have finite lives are amortized over their useful lives, which are generally based on contractual or legal rights. Finite-lived intangible assets are amortized in a manner consistent with the pattern in which the related benefits are expected to be consumed.
Impairment of Long-Lived Assets	Management reviews long-lived assets for impairment whenever events or changes in circumstances indicate that their carrying amounts may not be recoverable. If an evaluation is required, the estimated future undiscounted cash flows associated with the asset are compared with the asset’s carrying amount to determine if there has been an impairment, which is calculated as the difference between the fair value of an asset and its carrying value. Estimates of future undiscounted cash flows are based on expected growth rates for the business, anticipated future economic conditions and estimates of residual values. Fair values take into consideration management’s estimates of risk-adjusted discount rates, which are believed to be consistent with assumptions that marketplace participants would use in their estimates of fair value.
Goodwill and Indefinite-Lived Intangible Assets	Goodwill and Indefinite-Lived Intangible Assets The Company has goodwill and certain indefinite-lived intangible assets that have been recorded in connection with its acquisitions of businesses. Goodwill and indefinite-lived intangible assets are not amortized, but instead are tested for impairment at least annually. The Company performs its annual impairment tests of goodwill and indefinite-lived intangible assets during the fourth quarter of each year, and on a quarterly basis, management monitors these assets for potential impairment triggers. Goodwill is required to be tested for impairment at the reporting unit level. A reporting unit is an operating segment or one level below the operating segment level, which is referred to as a component. Management identifies its reporting units by assessing whether components (i) have discrete financial information available; (ii) engage in business activities; and (iii) have a segment manager regularly review the component’s operating results. Net assets and goodwill of acquired businesses are allocated to the reporting unit associated with the acquired business based on the organizational structure of the combined entities. If two or more components are deemed economically similar, those components are aggregated into one reporting unit when performing the annual goodwill impairment review.
Valuation of Net Assets Acquired and Earn-Out Liabilities	Valuation of Net Assets Acquired and Earn-Out Liabilities The determination of the fair value of net assets acquired in a business combination requires estimates and judgments of future cash flow expectations for the acquired business and the related identifiable tangible and intangible assets. Fair values are calculated using expected cash flows and industry-standard valuation techniques. For current assets and current liabilities, book value is generally assumed to equal fair value. Goodwill is the amount by which consideration paid exceeds the fair value of acquired net assets. Acquisition costs, including acquisition integration costs, are expensed as incurred and are included within general and administrative expenses in the consolidated statements of operations. Consideration paid generally consists of cash, common stock and potential future payments that are contingent upon the acquired business achieving certain levels of earnings in the future, also referred to as “acquisition-related contingent consideration” or “earn-out” payments. Earn-out liabilities are measured at their estimated fair value as of the date of acquisition, with subsequent changes in fair value recorded within other income or expense in the consolidated statements of operations. Fair value as of the date of acquisition is estimated based on projections of expected future cash flows of the acquired business. Subsequent to the date of acquisition, if future earn-out payments are expected to exceed earn-out payments estimated as of the date of acquisition, then a loss would be recognized in the period in which that expectation is considered probable. Conversely, if future earn-out payments are expected to be less than earn-out payments estimated as of the date of acquisition, a gain would be recognized in the period in which that expectation is considered probable. Acquisition-related contingent consideration is included within other current and other long-term liabilities, as appropriate, within the consolidated balance sheets. Due to the time required to gather and analyze the necessary data for each acquisition, U.S. GAAP provides a “measurement period” of up to one year in which to finalize these fair value determinations. During the measurement period, preliminary fair value estimates may be revised if new information is obtained about the facts and circumstances existing as of the date of acquisition based on the final net assets and net working capital of the acquired business, as prescribed in the applicable purchase agreements. Such adjustments may result in the recognition of, or adjust the fair values of, acquisition-related assets and liabilities and/or consideration paid. For the year ended December 31, 2017, measurement period adjustments included certain adjustments to the preliminary estimates of intangible assets and acquisition-related contingent consideration, and resulted in a net increase of approximately $2.7 million in estimated goodwill for businesses acquired in 2017. Fair value adjustments resulting from circumstances that developed after the date of acquisition are reflected as income or expense, as appropriate, in the period the adjustment is considered probable.
Fair Value of Financial Instruments	Fair Value of Financial Instruments The Company’s financial instruments include cash and cash equivalents, accounts and notes receivable, cash collateral deposited with insurance carriers, life insurance assets, equity investments, deferred compensation plan assets and liabilities, accounts payable and other current liabilities, acquisition-related contingent consideration and debt obligations. Fair value is the price that would be received to sell an asset or paid to transfer a liability (an exit price) in the principal or most advantageous market for the asset or liability in an orderly transaction between market participants on the measurement date. The fair value guidance establishes a valuation hierarchy, which requires maximizing the use of observable inputs when measuring fair value. The three levels of inputs that may be used are: (i) Level 1 - quoted market prices in active markets for identical assets or liabilities; (ii) Level 2 - observable market-based inputs or other observable inputs; and (iii) Level 3 - significant unobservable inputs that cannot be corroborated by observable market data, which are generally determined using valuation models incorporating management estimates of market participant assumptions. In instances in which the inputs used to measure fair value fall into different levels of the fair value hierarchy, the fair value measurement classification is determined based on the lowest level input that is significant to the fair value measurement in its entirety. Management’s assessment of the significance of a particular item to the fair value measurement in its entirety requires judgment, including the consideration of inputs specific to the asset or liability. Fair values of financial instruments are estimated using public market prices, quotes from financial institutions and other available information. Due to their short-term maturity, the carrying amounts of cash and cash equivalents, accounts receivable, accounts payable and other current liabilities approximate their fair values. Management believes the carrying values of notes and other receivables, cash collateral deposited with insurance carriers, deferred compensation plan assets and liabilities and outstanding balances on its credit facilities approximate their fair values.
Deferred Financing Costs	Deferred Financing Costs Deferred financing costs relate to the Company’s debt instruments, the short and long-term portions of which are reflected as a deduction from the carrying amount of the related debt instrument, including the Company’s credit facility. Deferred financing costs are amortized over the terms of the related debt instruments using the effective interest method.
Self-Insurance	Self-Insurance The Company is self-insured up to the amount of its deductible for its insurance policies. MasTec maintains insurance policies subject to per claim deductibles of $1.5 million for its workers’ compensation policy, $3.0 million for its general liability policy and $3.0 million for its automobile liability policy. The Company has excess umbrella coverage up to $100.0 million per claim and in the aggregate. Liabilities under these insurance programs are accrued based upon management’s estimates of the ultimate liability for claims reported and an estimate of claims incurred but not reported, with assistance from third-party actuaries. MasTec also maintains an insurance policy with respect to employee group medical claims, which is subject to annual per employee maximum losses of $0.5 million. MasTec’s liability for employee group medical claims is based on statistical analysis of historical claims experience and specific knowledge of actual losses that have occurred. The Company is also required to post letters of credit and provide cash collateral to certain of its insurance carriers and to obtain surety bonds in certain states. Cash collateral deposited with insurance carriers is included in other long-term assets in the consolidated balance sheets. The present value of the Company’s self-insurance liability is reflected in the consolidated balance sheets within current and other long-term liabilities, as appropriate. The determination of such claims and expenses and the appropriateness of the related liability is reviewed and updated quarterly, however, these insurance liabilities are difficult to assess and estimate due to unknown factors, including the severity of an injury, the determination of the Company’s liability in proportion to other parties and the number of incidents not reported. Accruals are based upon known facts and historical trends. Although management believes its accruals are adequate, a change in experience or actuarial assumptions could materially affect the Company’s results of operations in a particular period.
Income Taxes	Income Taxes The Company records income taxes using the asset and liability method of accounting for deferred income taxes. Under this method, deferred tax assets and liabilities are recognized for the expected future tax consequence of temporary differences between the financial statement and income tax basis of the Company’s assets and liabilities. Income taxes are estimated in each of the jurisdictions in which the Company operates. This process involves estimating the tax exposure, together with assessing temporary differences resulting from differing treatment of items, such as deferred revenue, for tax and accounting purposes. These differences result in deferred tax assets and liabilities, which are included within the consolidated balance sheets as net long-term assets and/or liabilities, as appropriate. The recording of a deferred tax asset assumes the realization of such asset in the future. Otherwise, a valuation allowance is recorded to reduce the asset to its estimated net realizable value. If management determines that the Company may not be able to realize all or part of a deferred tax asset in the future, a valuation allowance for the deferred tax asset is charged to income tax expense in the period the determination is made. Management considers future pretax income and ongoing prudent and feasible tax planning strategies in assessing the estimated net realizable value of tax assets and the corresponding need for a valuation allowance. The Company adopted Accounting Standards Update 2015-17, Income Taxes (Topic 740): Balance Sheet Classification of Deferred Taxes (“ASU 2015-17”) effective January 1, 2017, which changed the classification requirements for deferred tax assets and liabilities. ASU 2015-17 requires long-term classification of all deferred tax assets and liabilities, rather than separately classifying deferred tax assets and liabilities based on their net current and non-current amounts, as was required under the previous guidance. The adoption of ASU 2015-17, which was adopted on a prospective basis, did not have a material effect on the Company’s consolidated financial statements. In determining the provision for income taxes, management uses an effective tax rate based on annual pre-tax income, statutory tax rates, permanent tax differences and tax planning opportunities in the various jurisdictions in which the Company operates. Significant factors that affect the annual effective tax rate include management’s assessment of certain tax matters, the location and amount of taxable earnings, changes in certain non-deductible expenses and expected credits. In December 2017, the 2017 Tax Act was enacted, which includes broad tax reforms that are applicable to the Company. Under the provisions of the 2017 Tax Act, the U.S. corporate tax rate decreased from 35% to 21% effective January 1, 2018. As a result, the Company’s U.S. deferred income tax balances were required to be remeasured in 2017. The Company completed an initial remeasurement of its deferred tax assets and liabilities as of December 31, 2017 as a result of this new tax law, which resulted in a non-cash tax benefit of $120.1 million for the year ended December 31, 2017. The 2017 Tax Act significantly changes how the U.S. taxes corporations for years after 2017, and requires complex computations to be performed that were not previously required under U.S. tax law. The provisions of the 2017 Tax Act will require significant judgments and estimates to be made, and management’s interpretations of these provisions could differ from those of the U.S. Treasury Department or the IRS, which has yet to promulgate most regulations implementing the 2017 Tax Act. As management completes its analysis of the 2017 Tax Act, adjustments to the provisional amounts that have been recorded may be required, which could materially affect the Company’s provision for income taxes in the period of adjustment. As of December 31, 2017, the Company has not made a provision for U.S. income taxes on unremitted foreign earnings because such earnings are considered to be insignificant. The Company and its subsidiaries file income tax returns in numerous tax jurisdictions, including U.S. federal, most U.S. states and certain foreign jurisdictions. Although management believes its calculations for tax returns are correct and the positions taken thereon are reasonable, the final outcome of income tax examinations could be materially different from the resolution management currently anticipates and the estimates that are reflected in the consolidated financial statements, which could materially affect the Company’s results of operations in a particular period. To the extent interest and penalties are assessed by taxing authorities, such amounts are accrued and included within income tax expense.
Unremitted Foreign Earnings	As of December 31, 2017, the Company has not made a provision for U.S. income taxes on unremitted foreign earnings because such earnings are considered to be insignificant.
Stock-Based Compensation	Stock-Based Compensation The Company has certain stock-based compensation plans, under which restricted stock awards and restricted stock units (together “restricted shares”) are available for issuance to eligible employees and directors. Non-cash stock-based compensation expense is included within general and administrative expense in the consolidated statements of operations. Share-based payments, to the extent they are compensatory, are recognized based on their grant date fair values. Forfeitures are recorded as they occur. The Company records a deferred tax asset, or future tax benefit, based on the amount of share-based compensation recognized in the financial statements over the vesting period of share-based awards. The Company adopted ASU 2016-09, Compensation - Stock Compensation (Topic 718): Improvements to Employee Share-Based Payment Accounting (“ASU 2016-09”) effective January 1, 2017, which changed the accounting for excess tax benefits and deficiencies, which represent the tax effect of differences between the fair value of a share-based award on the date of vesting and the date of grant. Under ASU 2016-09, excess tax benefits or tax deficiencies are recognized in the income statement, rather than as additional paid-in-capital as under the previous guidance, and are presented as operating cash flows, rather than as a financing activity. Additionally, this ASU allowed companies to account for forfeitures of share-based payments as they occur, and increased the amount of tax that can be withheld by an employer for employee tax withholdings without resulting in liability classification of an award. Payments to taxing authorities for such employee withholdings are required to be presented as financing activities in the consolidated statements of cash flows. The provisions of ASU 2016-09 that were applicable to the Company were adopted on a prospective basis. The requirement to classify payments to taxing authorities for employee withholdings as a financing activity was consistent with the Company’s existing methodology, therefore did not result in a change. The adoption of ASU 2016-09 is expected to result in volatility in income tax expense given that excess tax benefits and deficiencies are recognized in income tax expense in the periods in which they occur. The other components of this ASU did not have a material effect on the consolidated financial statements. See Note 2 - Earnings Per Share, Note 9 - Stock-Based Compensation and Other Employee Benefit Plans and Note 12 - Income Taxes for additional information. Grants of restricted shares are valued based on the closing market share price of MasTec’s common stock as reported on the New York Stock Exchange (the “market price”) on the date of grant. Compensation expense arising from restricted shares is recognized on a straight line basis over the vesting period. Grants of restricted shares have cliff vesting terms, which generally vest over a period of 3 years. Upon vesting of share-based awards, some of the underlying shares are generally sold to cover the required withholding taxes. However, some participants may choose the net share settlement method to cover withholding tax requirements, in which case shares are not issued, but are treated as common stock repurchases in the consolidated financial statements, as they reduce the number of shares that would have been issued upon vesting. The Company then pays the corresponding withholding taxes to the appropriate taxing authorities in cash on behalf of the recipient. In addition, shares have either been sold or withheld to cover withholding tax requirements and/or to cover the exercise price for past option exercises. Withheld shares, which are valued at the market price on the date of vesting or exercise, as applicable, are recorded as a reduction to additional paid-in capital and are reflected as a financing activity within the consolidated statements of cash flows. Shares withheld for employee taxes and the exercise price of options totaled approximately 138,519, 44,988, and 74,407 for the years ended December 31, 2017, 2016 and 2015, respectively. Total payments for employee tax obligations to taxing authorities for withheld shares were $6.2 million, $0.6 million and $1.1 million for the years ended December 31, 2017, 2016 and 2015, respectively. The Company has certain employee stock purchase plans under which shares of the Company’s common stock are available for purchase by eligible employees. These plans allow qualified employees to purchase MasTec, Inc. common stock at 85% of its fair market value at the lower of (i) the date of commencement of the offering period or (ii) the last day of the exercise period, as defined in the plan documents. The fair value of purchases under the Company’s employee stock purchase plans is estimated using the Black-Scholes option-pricing valuation model. The determination of fair value of stock-based awards using an option-pricing model is affected by the Company’s stock price as well as assumptions pertaining to several variables, including expected stock price volatility, the expected term of the award and the risk-free rate of interest. In the option-pricing model for the Company’s employee stock purchase plans, expected stock price volatility is based on historical volatility of the Company’s common stock. The expected term of the award is based on historical and expected exercise patterns and the risk-free rate of interest is based on U.S. Treasury yields. The Company has not paid dividends in the past, and does not anticipate paying dividends in the foreseeable future, and therefore uses an expected dividend yield of zero.
Collective Bargaining Agreements and Multiemployer Plans	Collective Bargaining Agreements and Multiemployer Plans Certain of MasTec’s subsidiaries, including certain subsidiaries in Canada, are party to various collective bargaining agreements with unions representing certain of their employees. These agreements require the subsidiaries party to the agreements to pay specified wages, provide certain benefits to their union employees and contribute certain amounts to multiemployer pension and other multiemployer benefit plans and trusts (“MEPPs”). These contributions are recorded as a component of employee wages and salaries within costs of revenue, excluding depreciation and amortization. Contributions are generally based on fixed amounts per hour per employee for employees covered under these plans. Multiemployer plan contribution rates are determined annually and assessed on a “pay-as-you-go” basis based on union employee payrolls. The Pension Protection Act of 2006, as amended, (the “PPA”) requires pension plans that are underfunded to improve their funding ratios within prescribed intervals based on their level of underfunding, under which benefit reductions may apply and/or participating employers could be required to make additional contributions. In addition, if a multiemployer defined benefit plan fails to satisfy certain minimum funding requirements, the Internal Revenue Service (the “IRS”) may impose on the employers contributing to such plan a non-deductible excise tax of 5% of the amount of the accumulated funding deficiency. Union payrolls cannot be determined for future periods because the number of union employees employed at any given time, and the plans in which they may participate, vary depending upon the location and number of ongoing projects at a given time and the need for union resources in connection with those projects. The collective bargaining agreements expire at various times and have typically been renegotiated and renewed on terms similar to the ones contained in the expiring agreements. Under current law pertaining to employers that are contributors to U.S.-registered multiemployer defined benefit plans, a plan’s termination, an employer’s voluntary withdrawal from, or the mass withdrawal of contributing employers from, an underfunded multiemployer defined benefit plan requires participating employers to make payments to the plan for their proportionate share of the multiemployer plan’s unfunded vested liabilities. These liabilities include an allocable share of the unfunded vested benefits of the plan for all plan participants, not only for benefits payable to participants of the contributing employer. As a result, participating employers may bear a higher proportion of liability for unfunded vested benefits if the other participating employers cease to contribute to, or withdraw from, the plan. The allocable portion of liability to participating employers could be more disproportionate if employers that have withdrawn from the plan are insolvent, or if they otherwise fail to pay their proportionate share of the withdrawal liability. If the Company is subject to a withdrawal liability, the related withdrawal charge is recorded as a component of employee wages and salaries within costs of revenue, excluding depreciation and amortization, with any related liability recorded within other current and/or other long-term liabilities, as appropriate. The Company’s participation in the multiemployer pension plans is evaluated by management on an ongoing basis.
Restructuring Activities	Restructuring Activities From time to time, the Company may incur costs to streamline its business operations. These streamlining efforts, which are designed to improve profitability, could include eliminating service offerings that no longer fit into the Company’s business plan, certain integration activities for acquired businesses, reducing or eliminating services or operations that do not produce adequate revenue or margins, or reducing costs of business units that need margin improvements. The costs associated with these efforts, which we refer to as restructuring charges, include such items as employee separation costs, lease termination expenses and losses on disposal of excess fixed assets. When these efforts are related to circumstances that are significant, unique in nature and outside of the course of the Company’s normal and periodic business streamlining efforts, the related amount of restructuring charges included within the consolidated financial statements is aggregated and accompanied by a discussion of the nature of such restructuring activities. Restructuring charges are included within the applicable line item(s) in the consolidated statement of operations based on the nature of the expense incurred.
Litigation and Contingencies	Litigation and Contingencies Accruals for litigation and contingencies are reflected in the consolidated financial statements based on management’s assessment, including advice of legal counsel, of the expected outcome of litigation or other dispute resolution proceedings and/or the expected resolution of contingencies. Liabilities for estimated losses are accrued if the potential loss from any claim or legal proceeding is considered probable and the amount can be reasonably estimated. Significant judgment is required in both the determination of probability of loss and the determination as to whether the amount is reasonably estimable. Accruals are based only on information available at the time of the assessment due to the uncertain nature of such matters. As additional information becomes available, management reassesses potential liabilities related to pending claims and litigation and may revise its previous estimates, which could materially affect the Company’s results of operations in a given period.
New Accounting Pronouncements	New Accounting Pronouncements Accounting Pronouncements To Be Adopted in 2018 Revenue Recognition In May 2014, the Financial Accounting Standards Board (“FASB”) issued Accounting Standards Update (“ASU”) 2014-09, Revenue from Contracts with Customers (Topic 606) (“ASU 2014-09”). The core principle of this ASU is that a company will recognize revenue when it transfers goods or services to customers in an amount that reflects the consideration to which it expects to be entitled in exchange for those goods or services. In doing so, companies will need to use judgment and make estimates when evaluating contract terms and other relevant facts and circumstances. Additionally, ASU 2014-09 requires enhanced disclosures about the nature, amount, timing and uncertainty of revenue and cash flows arising from customer contracts. In August 2015, the FASB issued ASU 2015-14, Revenue from Contracts with Customers (Topic 606): Deferral of the Effective Date, which delayed the effective date of ASU 2014-09 by one year. In 2016 and 2017, the FASB issued several accounting standards updates to clarify certain topics within ASU 2014-09, and to update certain other topics within the Accounting Standards Codification (“ASC”) to conform with the new guidance in Topic 606. The Company adopted ASU 2014-09, and its related ASUs, under the modified retrospective transition approach as of January 1, 2018, which applies to all new contracts initiated on or after January 1, 2018. For existing contracts that have not been substantially completed as of January 1, 2018, any difference between the recognition criteria in these ASUs and the Company’s current revenue recognition practices will be recognized using a cumulative effect adjustment to the opening balance of retained earnings as of January 1, 2018. The Company’s assessment of the effects of Topic 606 on its consolidated financial statements, financial statement disclosures, business processes, systems and controls included a detailed review of representative contracts at each of the Company’s business units and a comparison of its historical accounting policies and practices to Topic 606 as well as the information necessary to enable the preparation of the financial statements and related disclosures under the new standard, including its information technology capabilities and systems. Based on the Company’s review of its revenue arrangements, the Company expects to recognize revenue and earnings over time utilizing the cost-to-cost measure of progress for its fixed price contracts and certain master service and other service agreements, consistent with current practice. For these contracts, the cost-to-cost measure of progress best depicts the transfer of control of goods or services to the customer under Topic 606. Contracts recognized over time are typically comprised of a single performance obligation as the promise to transfer the individual goods or services is not distinct from other promises in the contract due to the significant integration services provided by the Company in connection with its contracts. For certain contracts governed by a master service or other service agreement, revenue will be recognized at the point in time when control has been transferred to the customer, which is generally when the work order has been fulfilled, as control is not continuously transferred to the customer as the services are provided. Contract modifications are routine in the performance of the Company’s contracts and are typically evidenced by a change order. In most instances, change orders relate to adjustments to prices and the scope of services provided, which are not distinct from the scope of services in the original contract. Therefore, change orders will typically be accounted for on a cumulative catch-up basis under Topic 606, consistent with the Company’s current practice. The Company’s future disclosures related to revenue recognition will include information about unsatisfied performance obligations and expectations of the timing of recognition for those obligations. The disclosure pertaining to unsatisfied performance obligations will be in addition to the Company’s existing unaudited backlog disclosure, which represents the amount of revenue the Company expects to recognize over the next 18 months. The future disclosure pertaining to unsatisfied performance obligations will include the full amount of any unsatisfied performance obligations, as compared with only the amount expected to be recognized over the next 18 months, and it will exclude estimates of future revenue under master service and other service agreements. Additionally, in the future, the Company’s disclosures will reflect the amount of contract assets and contract liabilities, as calculated on a by-contract basis. Based on the Company’s evaluation of its systems and information technology capabilities, the Company does not expect to incur significant information technology costs to modify its systems to be able to achieve the preparation and disclosure requirements of the new standard, however, has implemented targeted changes to its internal reporting processes to facilitate gathering the data needed for the reporting and disclosure requirements. The Company also implemented a training program for its business units related to implementation of Topic 606 and continues to develop the required disclosures. The Company has also implemented updates to its control processes and procedures based on changes resulting from Topic 606. The adoption of Topic 606 is not expected to have a material effect on the timing or amount of revenue recognized as compared to current practices, or to have a material effect on the Company’s internal controls over financial reporting. Based on review of existing contracts that have not been substantially completed as of January 1, 2018, the Company has estimated that the cumulative adjustment to beginning retained earnings resulting from the adoption of Topic 606 will not be material. Other Accounting Pronouncements To Be Adopted in 2018 In January 2017, the FASB issued ASU 2017-04, Intangibles - Goodwill and Other (Topic 350): Simplifying the Test for Goodwill Impairment (“ASU 2017-04”). ASU 2017-04 eliminates the second step in goodwill impairment testing, which requires that goodwill impairment losses be measured as the difference between the implied value of a reporting unit’s goodwill and its carrying amount. ASU 2017-04, which the Company early adopted as of January 1, 2018, is expected to reduce the cost and complexity of impairment testing by requiring goodwill impairment losses to be measured as the excess of the reporting unit’s carrying amount, including goodwill and related goodwill tax effects, over its fair value. Beginning in 2018, if the carrying value of a reporting unit’s goodwill exceeds its implied value, the resulting amount of goodwill impairment recorded in the Company’s consolidated financial statements could differ from the amount of goodwill impairment that would have been recorded prior to adoption of this ASU. Additionally, the FASB issued ASU 2017-01, Business Combinations (Topic 805): Clarifying the Definition of a Business (“ASU 2017-01”) in January 2017. ASU 2017-01 changes the definition of a business for purposes of evaluating whether a transaction represents an acquisition (or disposal) of assets or a business. The revised definition of a business under ASU 2017-01 will reduce the number of transactions that are accounted for as business combinations. ASU 2017-01, which the Company adopted as of January 1, 2018, is not expected to have a material effect on the consolidated financial statements. In May 2017, FASB issued ASU 2017-09, Compensation - Stock Compensation (Topic 718): Scope of Modification Accounting (“ASU 2017-09”). ASU 2017-09 clarifies when a change to the terms or conditions of a share-based payment award must be accounted for as a modification. Limited and administrative modifications that do not change the value, vesting conditions, or classification of the award are exempt from following the modification guidance in Topic 718. This ASU, which the Company adopted as of January 1, 2018, is not expected to have a material effect on the consolidated financial statements. In October 2016, the FASB issued ASU 2016-16, Income Taxes (Topic 740): Intra-Entity Transfers of Assets Other Than Inventory (“ASU 2016-16”), which eliminates the existing exception in U.S. GAAP prohibiting the recognition of the income tax consequences for intra-entity asset transfers. Under ASU 2016-16, entities will be required to recognize the income tax consequences of intra-entity asset transfers, other than for inventory, when the transfer occurs. ASU 2016-16, which the Company adopted as of January 1, 2018, will not have a material effect on the Company’s consolidated financial statements. In August 2016, the FASB issued ASU 2016-15, Statement of Cash Flows (Topic 230): Classification of Certain Cash Receipts and Cash Payments (“ASU 2016-15”) to reduce diversity in practice by providing guidance on the classification of certain cash receipts and payments in the statement of cash flows. This ASU, which the Company adopted as of January 1, 2018, is effective on a retrospective basis, and will result in the reclassification of certain types of activity in the consolidated statement of cash flows, as applicable to the prior year periods, beginning in 2018. For the year ended December 31, 2017, acquisition-related contingent consideration payments in excess of acquisition date liabilities totaling approximately $12 million will be reclassified from financing to operating cash flows. Proceeds from the settlement of insurance claims related to damaged property and equipment, which are required to be reclassified from operating to investing cash flows, were not material for the years ended December 31, 2017, 2016 or 2015. The other provisions of this ASU are not expected to have a material effect on the Company’s consolidated financial statements. In January 2016, the FASB issued ASU 2016-01, Financial Instruments - Overall (Subtopic 825-10): Recognition and Measurement of Financial Assets and Financial Liabilities (“ASU 2016-01”), which provides guidance for the recognition, measurement, presentation and disclosure of financial assets and financial liabilities. ASU 2016-01 requires equity investments with readily determinable fair values, except for those accounted for under the equity method of accounting or those that are consolidated, to be measured at fair value with changes in fair value recognized in net income. Equity investments that do not have readily determinable fair values are permitted to be remeasured upon the occurrence of an observable price change or upon identification of an impairment. ASU 2016-01 also requires enhanced disclosures for such investments and modifies certain other disclosure requirements. This ASU, which the Company adopted as of January 1, 2018, is effective on a modified retrospective basis, with exception for the amendments related to equity investments without readily determinable fair values, which is effective prospectively. The adoption of ASU 2016-01 may result in volatility in other income (expense), net, as a result of the remeasurement requirements for equity investments; however, the Company does not expect such changes to be material. The other components of this ASU are not expected to have a material effect on the Company’s consolidated financial statements. Other Recent Accounting Pronouncements In February 2018, the FASB issued ASU 2018-02, Income Statement - Reporting Comprehensive Income (Topic 220): Reclassification of Certain Tax Effects from Accumulated Other Comprehensive Income (“ASU 2018-02”). ASU 2018-02 permits entities to reclassify the tax effects related to the change in the federal tax rate as a result of the 2017 Tax Act from accumulated other comprehensive income to retained earnings. The guidance may be applied retrospectively or in the period of adoption. ASU 2018-02 is effective for fiscal years, and for interim periods within those fiscal years, beginning after December 15, 2018, with early adoption permitted. The Company is currently evaluating the effect of this ASU on its consolidated financial statements. In August 2017, the FASB issued ASU 2017-12, Derivatives and Hedging (Topic 815): Targeted Improvements to Accounting for Hedging Activities (“ASU 2017-12”). ASU 2017-12 amends the hedge accounting model in Topic 815 to enable entities to better portray the economics of their risk management activities in the financial statements and enhance the transparency and understandability of hedge results. The guidance eliminates the requirement to separately measure and report hedge ineffectiveness and generally requires the entire change in the fair value of a hedging instrument to be presented in the same income statement line as the hedged item. The guidance also simplifies certain documentation and assessment requirements. ASU 2017-12 is effective for fiscal years, and for interim periods within those fiscal years, beginning after December 15, 2018, with early adoption permitted. All transition requirements and elections should be applied to hedging relationships existing on the date of adoption and their effects should be reflected as of the beginning of the fiscal year of adoption. The presentation and disclosure requirements are effective on a prospective basis. The Company is currently evaluating the potential effect of this ASU on its consolidated financial statements. In February 2016, the FASB issued ASU 2016-02, Leases (Subtopic 842) (“ASU 2016-02”). ASU 2016-02 provides revised guidance for lease accounting and related disclosure requirements, including a requirement for lessees to recognize lease assets and lease liabilities for certain operating leases. Under the previous guidance, lessees were not required to recognize assets and liabilities for operating leases on the balance sheet. ASU 2016-02 is effective for fiscal years, and for interim periods within those fiscal years, beginning after December 15, 2018, with early adoption permitted. Modified retrospective application is required for all relevant prior periods. The Company is currently evaluating the potential effect of this ASU on its consolidated financial statements, including the potential amount of incremental lease assets and liabilities that are expected to be recognized upon adoption.
Comprehensive Income	Comprehensive Income (Loss) Comprehensive income (loss) is a measure of net income (loss) and other changes in equity that result from transactions other than those with shareholders. Comprehensive income (loss) consists of net income (loss), foreign currency translation adjustments, primarily from fluctuations in foreign currency exchange rates of the Company’s foreign subsidiaries with a functional currency other than the U.S. dollar, unrealized gains and losses from investment activities and net income (loss) attributable to non-controlling interests.
Income Tax Uncertainties	An entity may only recognize or continue to recognize tax positions that meet a "more likely than not" threshold. In the ordinary course of business, there is inherent uncertainty in quantifying income tax positions. The Company assesses its income tax positions and records tax benefits for all years subject to examination based on management's evaluation of the facts, circumstances and information available at the reporting date. For those tax positions where it is more likely than not that a tax benefit will be sustained, the Company has recognized the largest amount of tax benefit with a greater than 50% likelihood of being realized upon ultimate settlement with a taxing authority that has full knowledge of all relevant information. For those income tax positions where it is not more likely than not that a tax benefit will be sustained, no tax benefit has been recognized in the Company's financial statements.

Earnings Per Share (Tables)

12 Months Ended

Dec. 31, 2017

Earnings Per Share [Abstract]

Schedule of Earnings Per Share Information

The following table provides details underlying the Company’s earnings per share calculations for the periods indicated (in thousands):



	For the Years Ended December 31,
	2017		2016		2015
Net income (loss) attributable to MasTec:
Net income (loss) - basic and diluted^(a)	$	347,213	$	131,263	$	(79,110	)
Weighted average shares outstanding:
Weighted average shares outstanding - basic	80,903		80,372		80,489
Dilutive common stock equivalents	1,422		1,022		—
Weighted average shares outstanding - diluted	82,325		81,394		80,489

Additional information:
Weighted average anti-dilutive common stock equivalents ^(b)	—		31		564


(a)	Calculated as total net income (loss) less amounts attributable to non-controlling interests.


(b)	For the year ended December 31, 2016, represents anti-dilutive common stock equivalents as calculated under the treasury stock method, and, for the year ended December 31, 2015, represents anti-dilutive common stock equivalents due to the Company having reported a net loss.

Goodwill and Other Intangible Assets (Tables)

12 Months Ended

Dec. 31, 2017

Goodwill and Intangible Assets Disclosure [Abstract]

Rollforward of Goodwill by Reportable Segment

The following table provides a reconciliation of changes in goodwill by reportable segment for the periods indicated (in millions):



	Communications		Oil and Gas			Electrical Transmission		Power Generation and Industrial		Total Goodwill
Goodwill, gross, as of December 31, 2015	$	414.9	$	374.6		$	149.9	$	117.6	$	1,057.0
Accumulated impairment loss ^(a)	—		(68.5		)	—		—		(68.5		)
Goodwill, net, as of December 31, 2015	$	414.9	$	306.1		$	149.9	$	117.6	$	988.5
Accruals of acquisition-related contingent consideration, net^(b)	5.8		—			—		—		5.8
Currency translation adjustments	—		1.6			—		—		1.6
Goodwill, net, as of December 31, 2016	$	420.7	$	307.7		$	149.9	$	117.6	$	995.9
Additions from new business combinations	45.7		74.1			—		18.2		138.0
Currency translation adjustments	—		3.8			—		—		3.8
Goodwill, net, as of December 31, 2017	$	466.4	$	385.6		$	149.9	$	135.8	$	1,137.7
Accumulated impairment loss ^(a)	—		(74.8		)	—		—		(74.8		)
Goodwill, gross, as of December 31, 2017	$	466.4	$	460.4		$	149.9	$	135.8	$	1,212.5


(a)	Accumulated impairment losses include the effect of currency translation gains and/or losses.


(b)	Represents contingent consideration for acquisitions prior to January 1, 2009, which is accrued as incurred, in accordance with U.S. GAAP.

Rollforward of Other Intangible Assets

The following table provides a reconciliation of changes in other intangible assets for the periods indicated (in millions):



	Other Intangible Assets
	Non-amortizing					Amortizing
	Trade Names			Pre-Qualifications		Customer Relationships and Backlog			Other ^(a)			Total
Other intangible assets, gross, as of December 31, 2015	$	34.8		$	73.4	$	195.4		$	25.7		$	329.3
Accumulated amortization						(114.6		)	(15.3		)	(129.9		)
Other intangible assets, net, as of December 31, 2015	$	34.8		$	73.4	$	80.8		$	10.4		$	199.4
Amortization expense						(17.9		)	(3.4		)	(21.3		)
Currency translation adjustments	—			1.2		0.3			0.1			1.6
Other activity	(0.3		)	—		—			0.3			—
Other intangible assets, net, as of December 31, 2016	$	34.5		$	74.6	$	63.2		$	7.4		$	179.7
Additions from new business combinations	—			—		26.3			2.5			28.8
Amortization expense						(19.3		)	(1.6		)	(20.9		)
Currency translation adjustments	—			3.0		0.4			0.1			3.5
Other intangible assets, net, as of December 31, 2017	$	34.5		$	77.6	$	70.6		$	8.4		$	191.1
Remaining weighted average amortization period (in years)						9			8			9


(a)	Consists principally of trade names and non-compete agreements.

Schedule of Expected Future Amortization Expense

Expected future amortization expense as of December 31, 2017 is summarized in the following table (in millions):



	Amortization Expense
2018	$	19.5
2019	13.4
2020	11.0
2021	8.4
2022	6.9
Thereafter	19.8
Total	$	79.0

Schedule of Consideration Paid and Net Assets Acquired, Business Combinations

The following table summarizes the estimated fair values of consideration paid and net assets acquired as of the respective dates of acquisition, as adjusted (in millions):



Acquisition consideration:	2017
Cash	$	117.9
Fair value of contingent consideration (earn-out liability)	93.5
Total consideration transferred	$	211.4
Identifiable assets acquired and liabilities assumed:
Current assets, primarily composed of accounts receivable and $2.8 million of cash acquired	$	42.7
Property and equipment	56.7
Amortizing intangible assets	28.8
Other long-term assets	0.5
Current liabilities, including current portion of capital lease obligations and long-term debt	(29.2		)
Long-term debt, including capital lease obligations	(9.9		)
Deferred income taxes	(16.2		)
Total identifiable net assets	$	73.4
Goodwill	$	138.0
Total net assets acquired, including goodwill	$	211.4

Fair Value of Financial Instruments (Tables)

12 Months Ended

Dec. 31, 2017

Fair Value Disclosures [Abstract]

Schedule of Summarized Financial Information of Equity Method Investments

Summarized Financial Information of Equity Method Investments

The following presents summarized information for the Company’s significant equity method investments (in millions):



	December 31,
	2017		2016
Current assets	$	136.8	$	89.5
Long-term assets	1,306.3		1,126.5
Total assets	$	1,443.1	$	1,216.0

Current liabilities	$	121.2	$	153.6
Long-term liabilities	976.5		986.0
Total liabilities	$	1,097.7	$	1,139.6



	For the Years Ended December 31,
	2017		2016			2015
Revenue	$	114.5	$	—		$	—
Net income (loss)	$	64.5	$	(0.2	)	$	(13.3	)

Accounts Receivable, Net of Allowance (Tables) - Accounts Receivable [Member]

12 Months Ended

Dec. 31, 2017

Schedule of Accounts Receivable, Net of Allowance [Line Items]

Schedule of Accounts Receivable, Net of Allowance

The following table provides details of accounts receivable, net of allowance, as of the dates indicated (in millions):



	December 31,
	2017			2016
Contract billings	$	683.9		$	564.2
Retainage	323.1			268.6
Costs and earnings in excess of billings	599.2			331.6
Accounts receivable, gross	$	1,606.2		$	1,164.4
Less allowance for doubtful accounts	(8.2		)	(8.4		)
Accounts receivable, net	$	1,598.0		$	1,156.0

Schedule of Activity, Allowance for Doubtful Accounts

Activity in the allowance for doubtful accounts for the periods indicated is as follows (in millions):



	For the Years Ended December 31,
	2017			2016
Allowance for doubtful accounts at beginning of year	$	8.4		$	7.7
Provision for doubtful accounts	2.6			2.9
Amounts charged against the allowance	(2.8		)	(2.2		)
Allowance for doubtful accounts at end of year	$	8.2		$	8.4

Property and Equipment, Net (Tables)

12 Months Ended

Dec. 31, 2017

Property, Plant and Equipment [Abstract]

Schedule of Property and Equipment, Net

The following table provides details of property and equipment, net, including property and equipment held under capital leases as of the dates indicated (in millions):



	December 31,
	2017			2016			Estimated Useful Lives (in years)
Land	$	4.6		$	4.6
Buildings and leasehold improvements	26.7			24.2			3-40
Machinery and equipment	1,261.9			997.8			2-20
Office furniture and equipment	149.9			146.1			3-7
Construction in progress	12.5			9.5
Total property and equipment	$	1,455.6		$	1,182.2
Less accumulated depreciation and amortization	(749.1		)	(633.1		)
Property and equipment, net	$	706.5		$	549.1

Debt (Tables)

12 Months Ended

Dec. 31, 2017

Debt Disclosure [Abstract]

Schedule of Carrying Values of Debt

The following table provides details of the carrying values of debt as of the dates indicated (in millions):



		December 31,
Description	Maturity Date	2017			2016
Senior secured credit facility:	February 22, 2022
Revolving loans		$	377.7		$	279.9
Term loan		396.9			237.5
4.875% Senior Notes	March 15, 2023	400.0			400.0
Capital lease obligations, weighted average interest rate of 3.5%	In installments through September 1, 2022	181.2			98.6
Other debt obligations	Varies	25.8			19.8
Total long-term debt obligations		$	1,381.6		$	1,035.8
Less unamortized deferred financing costs		(13.0		)	(9.8		)
Total debt, net of deferred financing costs		$	1,368.6		$	1,026.0
Current portion of long-term debt		87.9			64.6
Long-term debt		$	1,280.7		$	961.4

Schedule of Contractual Maturities of Debt and Capital Lease Obligations

Contractual maturities of MasTec’s debt and capital lease obligations as of December 31, 2017 were as follows (in millions):



2018	$	88.3
2019	65.5
2020	57.0
2021	46.4
2022	724.4
Thereafter	400.0
Total	$	1,381.6

Schedule of Future Lease Commitments

Tabular disclosure of long-debt instruments or arrangements, including identification, terms, features, collateral requirements and other information necessary to a fair presentation. These are debt arrangements that originally required repayment more than twelve months after issuance or greater than the normal operating cycle of the entity, if longer.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02.22)
-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 505
-SubTopic 10
-Section 50
-Paragraph 3
-URI http://asc.fasb.org/extlink&oid=84159872&loc=d3e21475-112644

Reference 3: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 942
-SubTopic 470
-Section 50
-Paragraph 3
-URI http://asc.fasb.org/extlink&oid=75038535&loc=d3e64711-112823

Reference 4: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 235
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.4-08.(e),(f))
-URI http://asc.fasb.org/extlink&oid=26873400&loc=d3e23780-122690

Reference 5: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 835
-SubTopic 30
-Section 55
-Paragraph 8
-URI http://asc.fasb.org/extlink&oid=64930739&loc=d3e28878-108400

Reference 6: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 505
-SubTopic 10
-Section 50
-Paragraph 8
-URI http://asc.fasb.org/extlink&oid=84159872&loc=d3e21538-112644

Reference 7: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 505
-SubTopic 10
-Section 50
-Paragraph 6
-URI http://asc.fasb.org/extlink&oid=84159872&loc=d3e21506-112644

Reference 8: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 835
-SubTopic 30
-Section 45
-Paragraph 1A
-URI http://asc.fasb.org/extlink&oid=64930785&loc=d3e28541-108399

Reference 9: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 835
-SubTopic 30
-Section 45
-Paragraph 2
-URI http://asc.fasb.org/extlink&oid=64930785&loc=d3e28551-108399

Reference 10: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 505
-SubTopic 10
-Section 50
-Paragraph 7
-URI http://asc.fasb.org/extlink&oid=84159872&loc=d3e21521-112644

+ Details

Lease Obligations (Tables)

12 Months Ended

Dec. 31, 2017

Leases [Abstract]

Future minimum lease commitments under capital leases and non-cancelable operating leases, including escalation clauses in effect as of December 31, 2017, were as follows (in millions):



	Capital Leases			Operating Leases
2018	$	69.5		$	90.7
2019	49.4			57.3
2020	39.4			33.9
2021	29.0			19.2
2022	9.1			12.3
Thereafter	—			30.3
Total minimum lease payments	$	196.4		$	243.7
Less amounts representing interest	(15.2		)
Total capital lease obligations, net of interest	$	181.2
Less current portion	(63.5		)
Long-term portion of capital lease obligations, net of interest	$	117.7

Stock-Based Compensation and Other Employee Benefit Plans (Tables)

12 Months Ended

Dec. 31, 2017

Share-based Compensation [Abstract]

Schedule of Activity, Restricted Shares



Activity, restricted shares: ^(a)	Restricted Shares		Per Share Weighted Average Grant Date Fair Value
Non-vested restricted shares, as of December 31, 2015	1,630,232		$	22.94
Granted	637,332		17.69
Vested	(188,386	)	20.42
Canceled/forfeited	(108,592	)	20.71
Non-vested restricted shares, as of December 31, 2016	1,970,586		$	21.61
Granted	429,061		40.46
Vested	(899,815	)	28.08
Canceled/forfeited	(51,241	)	18.22
Non-vested restricted shares, as of December 31, 2017	1,448,591		$	23.29


(a)	Includes 27,550, 43,300 and 32,250 restricted stock units as of December 31, 2017, 2016 and 2015, respectively.

Schedule of Activity, Employee Stock Purchase Plans

The following table provides details pertaining to the Company’s ESPPs for the periods indicated:



	For the Years Ended December 31,
	2017		2016		2015
Cash proceeds (in millions)	$	3.3	$	2.7	$	2.0
Common shares issued	92,145		144,183		134,389
Weighted average price per share	$	35.92	$	18.55	$	14.67
Weighted average per share grant date fair value	$	9.24	$	5.00	$	4.22

Schedule of Non-Cash Stock-Based Compensation Expense and Related Tax Effects

Details of non-cash stock-based compensation expense and related tax effects for the periods indicated were as follows (in millions):



	For the Years Ended December 31,
	2017		2016		2015
Non-cash stock-based compensation expense	$	15.7	$	15.1	$	12.4
Income Tax Effects:
Income tax effect of non-cash stock-based compensation	$	11.2	$	5.6	$	4.2
Excess tax benefit from non-cash stock-based compensation ^(a)	$	5.7	$	0.1	$	0.1


(a)	Excess tax benefits represent cash flows from tax deductions in excess of the tax effect of compensation expense associated with share-based payment arrangements. For the year ended December 31, 2017, the Company recognized a tax benefit of $5.4 million, net of tax deficiencies, related to the vesting of share-based payment awards.

Other Retirement Plans (Tables)

12 Months Ended

Dec. 31, 2017

Schedule of Covered Employees and Contributions, Multiemployer Plans



	Multiemployer Plans
	Covered Employees		Contributions (in millions)
For the Years Ended December 31:	Low	High	Pension		Other Multiemployer		Total
2017	550	7,057	$	92.1	$	10.3	$	102.4
2016	550	4,910	$	59.9	$	10.1	$	70.0
2015	590	2,463	$	23.8	$	9.0	$	32.8

Multiemployer Plans, Pension [Member]

Schedule of Multiemployer Pension Plans

Contributions

(in millions)

For the Years Ended December 31,

Pension Protection Act Zone Status

Multiemployer Pension Plan

Employer Identification Number

Plan Number

2017

2016

2015

Expiration Date of CBA

2017

As of

2016

As of

FIP/RP Status

Surcharge

Pipeline Industry Pension Fund

736146433

001

28.8

15.9

2.5

05/31/2020

Green

12/31/2016

(a)

Green

12/31/2015

(a)

Central Pension Fund of the IUOE and Participating Employers

366052390

001

21.6

19.3

5.7

06/01/2020

Green

01/31/2017

Green

01/31/2016

Teamsters National Pipe Line Pension Plan

461102851

001

7.6

3.6

1.4

05/31/2020

Green

12/31/2016

(a)

Green

12/31/2015

(a)

Ohio Operating Engineers Pension Plan

316129968

001

4.9

—

06/01/2020

Green

07/31/2016

Green

07/31/2015

Laborers' National Pension Fund

751280827

001

3.5

3.0

0.8

05/31/2020

Green

12/31/2016

Green

12/31/2015

West Virginia Laborers' Pension Trust Fund

556026775

001

3.0

0.5

1.4

05/31/2020

Green

03/31/2017

Green

03/31/2016

(a)

Laborers' District Council & Contractors Pension Fund of Ohio

316129964

001

2.5

0.5

0.2

05/31/2020

Green

12/31/2016

Green

12/31/2015

International Union of Operating Engineers Local 132 Pension Fund

556015364

001

2.3

0.2

1.9

06/01/2020

Green

03/31/2017

Green

03/31/2016

(a)

Operating Engineers Local 324 Pension Fund

381900637

001

2.1

—

06/01/2020

Red

04/30/2017

Red

04/30/2016

Implemented

Michigan Laborers' Pension Plan

386233976

001

2.0

1.1

0.8

05/31/2020

Yellow

08/31/2017

Yellow

08/31/2016

(b)

Implemented

National Electrical Benefit Fund

530181657

001

1.8

1.7

1.4

Varies through 09/06/2020

Green

12/31/2016

Green

12/31/2015

Laborers' Local Union No. 158 Pension Plan

236580323

001

1.8

0.4

0.7

05/31/2020

Green

12/31/2016

Green

12/31/2015

(a)

IBEW Local 1249 Pension Plan

156035161

001

1.5

1.1

1.0

05/02/2021

Yellow

12/31/2016

Yellow

12/31/2015

Implemented

Central Laborers' Pension Fund

376052379

001

0.5

2.6

—

05/31/2020

Yellow

12/31/2016

(b)

Red

12/31/2015

(b)

Implemented

Other funds

8.2

(c)

10.0

(c)

6.0

(c)

Total multiemployer pension plan contributions

92.1

59.9

23.8


(a)	The Company’s contributions to this plan represent greater than 5% of the plan’s total contributions.


(b)	This plan has utilized extended amortization provisions, which provide plans with extensions of time to amortize pension funding shortfalls.

(c)

Equity (Tables)

12 Months Ended

Dec. 31, 2017

Accumulated Other Comprehensive Loss

Schedule of Changes in Accumulated Other Comprehensive Loss

Activity for the periods indicated was as follows (in thousands):



	For the Years Ended December 31,
	2017									2016									2015
	Foreign Currency			Other			Total			Foreign Currency			Other			Total			Foreign Currency			Other			Total
Balance as of January 1	$	(64,478	)	$	(1,336	)	$	(65,814	)	$	(67,063	)	$	(5,288	)	$	(72,351	)	$	(28,716	)	$	(5,288	)	$	(34,004	)
Unrealized gains (losses), net of tax	1,627			475			2,102			2,585			3,952			6,537			(38,347		)	—			(38,347		)
Balance as of December 31	$	(62,851	)	$	(861	)	$	(63,712	)	$	(64,478	)	$	(1,336	)	$	(65,814	)	$	(67,063	)	$	(5,288	)	$	(72,351	)

Income Taxes (Tables)

12 Months Ended

Dec. 31, 2017

Income Tax Disclosure [Abstract]

Schedule of Components of Income (Loss) before Income Taxes

The components of income (loss) before income taxes for the periods indicated were as follows (in millions):



	For the Years Ended December 31,
	2017		2016		2015
Domestic	$	334.9	$	202.4	$	(26.5	)
Foreign	36.9		23.4		(41.2		)
Total	$	371.8	$	225.8	$	(67.7	)

Schedule of Provision for Income Taxes

The provision for income taxes for the periods indicated were as follows (in millions):



	For the Years Ended December 31,
	2017			2016			2015
Current:
Federal	$	(6.0	)	$	85.8		$	(4.5	)
Foreign	11.5			3.0			9.4
State and local	(0.8		)	6.7			3.3
	$	4.7		$	95.5		$	8.2
Deferred:
Federal	$	18.2		$	6.1		$	25.7
Foreign	(7.5		)	(6.8		)	(19.9		)
State and local	7.6			(3.0		)	(2.0		)
	$	18.3		$	(3.7	)	$	3.8
Provision for income taxes	$	22.9		$	91.8		$	12.0

Schedule of Deferred Tax Assets and Liabilities

The tax effects of significant items comprising the Company’s net deferred tax liability as of the dates indicated were as follows (in millions):



	December 31,
	2017			2016
Deferred tax assets:
Accrued insurance	$	24.6		$	31.1
Operating loss carryforwards and tax credits	54.9			34.9
Unrealized gains and losses	11.4			26.3
Compensation and benefits	7.5			24.1
Bad debt	1.2			4.7
Other	7.9			12.4
Valuation allowance	(40.5		)	(21.4		)
Total deferred tax assets	$	67.0		$	112.1
Deferred tax liabilities:
Property and equipment	$	104.1		$	126.6
Goodwill	56.7			72.8
Other intangible assets	28.7			32.9
Gain on remeasurement of equity investee	6.9			10.9
Long-term contracts	11.3			20.2
Investments in unconsolidated entities	52.8			0.0
Other	11.0			15.3
Total deferred tax liabilities	$	271.5		$	278.7
Net deferred tax liabilities	$	(204.5	)	$	(166.6	)

Schedule of Effective Tax Rate Reconciliation

A reconciliation of the U.S. statutory federal income tax rate related to pretax income to the effective tax rate for the periods indicated is as follows:



	For the Years Ended December 31,
	2017		2016		2015
U.S. statutory federal rate applied to pretax income (loss)	35.0	%	35.0	%	35.0	%
State and local income taxes, net of federal benefit	2.0		2.6		(1.0	)
Foreign tax rate differential	0.3		(0.1	)	(14.4	)
Non-deductible expenses	2.2		4.4		(13.5	)
Goodwill and intangible assets	(0.0	)	(0.7	)	(17.7	)
Change in tax rate	(32.3	)	(1.9	)	(3.6	)
Domestic production activities deduction	(0.2	)	(2.9	)	(1.0	)
Other	(0.7	)	(0.1	)	(1.4	)
Tax credits	(2.8	)	(0.0	)	(0.0	)
Valuation allowance for deferred tax assets	2.7		4.3		0.0
Effective income tax rate	6.2	%	40.6	%	(17.6	)%

Rollforward of Uncertain Tax Positions

A reconciliation of the beginning and ending amount of uncertain tax positions including interest and penalties is as follows (in millions):



	For the Years Ended December 31,
	2017		2016		2015
Beginning balance	$	—	$	—	$	—
Additions based on tax positions related to the current year	3.2		—		—
Additions for tax positions of prior years	4.9		—		—
Ending balance	$	8.1	$	—	$	—

Segments and Related Information (Tables)

12 Months Ended

Dec. 31, 2017

Segment Reporting [Abstract]

Schedule of Financial Information by Reportable Segment



	For the Years Ended December 31,
Revenue:	2017			2016			2015
Communications ^(a)	$	2,424.4		$	2,323.6		$	1,973.2
Oil and Gas	3,497.2			2,024.4			1,495.1
Electrical Transmission	378.2			383.8			341.5
Power Generation and Industrial	299.9			405.7			381.6
Other	20.8			15.9			24.1
Eliminations	(13.5		)	(18.7		)	(7.2		)
Consolidated revenue	$	6,607.0		$	5,134.7		$	4,208.3


(a)	Revenue generated primarily by utilities customers represented 13.4%, 11.1% and 10.6% of Communications segment revenue for the years ended December 31, 2017, 2016 and 2015, respectively.



	For the Years Ended December 31,
EBITDA:	2017			2016			2015
Communications	$	247.4		$	244.6		$	194.8
Oil and Gas	402.2			297.3			157.0
Electrical Transmission	17.6			(42.9		)	(71.3		)
Power Generation and Industrial	22.6			18.3			8.8
Other	19.8			(2.6		)	(18.8		)
Corporate	(88.7		)	(73.1		)	(120.5		)
Consolidated EBITDA	$	620.9		$	441.5		$	150.0



	For the Years Ended December 31,
Depreciation and Amortization:	2017		2016		2015
Communications	$	53.2	$	50.3	$	50.6
Oil and Gas	96.7		78.4		84.5
Electrical Transmission	22.8		23.2		21.1
Power Generation and Industrial	9.1		6.2		6.6
Other	0.1		0.1		0.1
Corporate	6.1		6.7		6.8
Consolidated depreciation and amortization	$	188.0	$	164.9	$	169.7



	As of December 31,
Assets:	2017		2016		2015
Communications	$	1,314.4	$	1,156.9	$	1,032.2
Oil and Gas	1,762.6		1,267.2		1,131.4
Electrical Transmission	471.4		419.1		409.1
Power Generation and Industrial	288.6		268.1		252.5
Other	153.2		27.7		34.3
Corporate	76.4		44.1		67.8
Consolidated segment assets	$	4,066.6	$	3,183.1	$	2,927.3



	For the Years Ended December 31,
Capital Expenditures:	2017		2016		2015
Communications	$	40.5	$	28.5	$	25.8
Oil and Gas	57.7		64.0		38.1
Electrical Transmission	14.9		19.8		13.0
Power Generation and Industrial	5.4		3.4		3.5
Other	0.0		0.3		0.2
Corporate	4.9		1.1		3.8
Consolidated capital expenditures	$	123.4	$	117.1	$	84.4

Reconciliation of Consolidated Income (Loss) before Income Taxes to EBITDA



	For the Years Ended December 31,
EBITDA Reconciliation:	2017		2016		2015
Income (loss) before income taxes	$	371.8	$	225.8	$	(67.7	)
Plus:
Interest expense, net	61.0		50.7		48.1
Depreciation and amortization	188.0		164.9		169.7
Consolidated EBITDA	$	620.9	$	441.5	$	150.0

Schedule of Significant Customers, Revenue Concentration Information

Revenue concentration information for significant customers as a percentage of total consolidated revenue was as follows:



	For the Years Ended December 31,
	2017	2016	2015
Customer:
Energy Transfer affiliates ^(a)	40%	27%	7%
AT&T (including DIRECTV^®) ^(b)	25%	34%	32%


(a)	The Company's relationship with Energy Transfer affiliates is based upon various construction contracts for pipeline activities with Energy Transfer Partners L.P., and its subsidiaries and affiliates, all of which are consolidated by Energy Transfer Equity, L.P. Revenue from Energy Transfer affiliates is included in the Oil and Gas segment.

(b)

Quarterly Information (Unaudited) (Tables)

12 Months Ended

Dec. 31, 2017

Quarterly Financial Information Disclosure [Abstract]

Schedule of Quarterly Information (Unaudited)



	For the 2017 Quarters Ended								For the 2016 Quarters Ended
	March 31		June 30		September 30		December 31		March 31			June 30		September 30		December 31
Revenue	$	1,158.2	$	1,890.2	$	1,955.8	$	1,602.9	$	974.2		$	1,232.4	$	1,586.2	$	1,341.9
Costs of revenue, excluding depreciation and amortization	$	971.1	$	1,626.3	$	1,726.2	$	1,421.7	$	884.4		$	1,068.2	$	1,369.0	$	1,120.6
Net income (loss)	$	40.6	$	83.3	$	64.2	$	160.7	$	(2.9	)	$	24.4	$	56.5	$	55.9
Net income (loss) attributable to MasTec, Inc.	$	41.0	$	81.7	$	63.8	$	160.8	$	(2.7	)	$	24.1	$	56.3	$	53.6
Earnings (loss) per share:
Basic	$	0.51	$	1.01	$	0.79	$	1.98	$	(0.03	)	$	0.30	$	0.70	$	0.67
Diluted	$	0.50	$	0.99	$	0.77	$	1.95	$	(0.03	)	$	0.30	$	0.69	$	0.66

Supplemental Guarantor Financial Information (Tables)

12 Months Ended

Dec. 31, 2017

Condensed Financial Statements, Supplemental Guarantor Information [Abstract]

Condensed Consolidating Statements of Operations and Comprehensive Income (Loss)

CONDENSED CONSOLIDATING STATEMENTS OF OPERATIONS AND COMPREHENSIVE INCOME (LOSS) (in millions)



For the Year Ended December 31, 2017	MasTec, Inc.			Guarantor Subsidiaries			Non-Guarantor Subsidiaries			Eliminations			Consolidated MasTec, Inc.
Revenue	$	—		$	6,222.3		$	457.0		$	(72.3	)	$	6,607.0
Costs of revenue, excluding depreciation and amortization	—			5,378.6			439.0			(72.3		)	5,745.3
Depreciation and amortization	—			159.1			28.9			—			188.0
General and administrative expenses	2.3			256.3			16.5			—			275.1
Interest expense (income), net	—			123.6			(62.6		)	—			61.0
Equity in earnings of unconsolidated affiliates	—			—			(21.3		)	—			(21.3		)
Other income, net	—			(13.0		)	—			—			(13.0		)
(Loss) income before income taxes	$	(2.3	)	$	317.7		$	56.5		$	—		$	371.8
Benefit from (provision for) income taxes	0.2			(18.1		)	(5.0		)	—			(22.9		)
Net (loss) income before equity in income from subsidiaries	$	(2.1	)	$	299.6		$	51.5		$	—		$	348.9
Equity in income from subsidiaries, net of tax	349.3			—			—			(349.3		)	—
Net income (loss)	$	347.2		$	299.6		$	51.5		$	(349.3	)	$	348.9
Net income (loss) attributable to non-controlling interests	—			2.4			(0.7		)	—			1.7
Net income (loss) attributable to MasTec, Inc.	$	347.2		$	297.2		$	52.2		$	(349.3	)	$	347.2
Comprehensive income (loss)	$	349.3		$	299.6		$	53.6		$	(351.4	)	$	351.0

CONDENSED CONSOLIDATING STATEMENTS OF OPERATIONS AND COMPREHENSIVE INCOME (LOSS) (in millions)



For the Year Ended December 31, 2016	MasTec, Inc.			Guarantor Subsidiaries			Non-Guarantor Subsidiaries			Eliminations			Consolidated MasTec, Inc.
Revenue	$	—		$	4,790.9		$	353.8		$	(10.0	)	$	5,134.7
Costs of revenue, excluding depreciation and amortization	—			4,101.2			350.9			(10.0		)	4,442.1
Depreciation and amortization	—			134.2			30.7			—			164.9
General and administrative expenses	2.4			234.4			24.6			—			261.4
Interest expense (income), net	—			112.0			(61.3		)	—			50.7
Equity in earnings of unconsolidated affiliates	—			—			(3.5		)	—			(3.5		)
Other income, net	—			—			(6.8		)	—			(6.8		)
(Loss) income before income taxes	$	(2.4	)	$	209.1		$	19.2		$	—		$	225.8
Benefit from (provision for) income taxes	0.9			(72.6		)	(20.1		)	—			(91.8		)
Net (loss) income before equity in income from subsidiaries	$	(1.5	)	$	136.5		$	(0.9	)	$	—		$	134.0
Equity in income from subsidiaries, net of tax	132.8			—			—			(132.8		)	—
Net income (loss)	$	131.3		$	136.5		$	(0.9	)	$	(132.8	)	$	134.0
Net income (loss) attributable to non-controlling interests	—			3.3			(0.5		)	—			2.8
Net income (loss) attributable to MasTec, Inc.	$	131.3		$	133.2		$	(0.4	)	$	(132.8	)	$	131.3
Comprehensive income (loss)	$	137.8		$	136.5		$	5.6		$	(139.3	)	$	140.6



For the Year Ended December 31, 2015	MasTec, Inc.			Guarantor Subsidiaries			Non-Guarantor Subsidiaries			Eliminations			Consolidated MasTec, Inc.
Revenue	$	—		$	3,527.0		$	689.7		$	(8.4	)	$	4,208.3
Costs of revenue, excluding depreciation and amortization	—			3,073.6			656.1			(8.4		)	3,721.3
Depreciation and amortization	—			130.6			39.1			—			169.7
Goodwill and intangible asset impairment	—			—			78.6			—			78.6
General and administrative expenses	2.1			235.4			28.4			—			265.9
Interest expense (income), net	—			111.0			(62.9		)	—			48.1
Equity in losses of unconsolidated affiliates	—			—			8.0			—			8.0
Other income, net	—			(6.2		)	(9.3		)	—			(15.5		)
Loss before income taxes	$	(2.1	)	$	(17.4	)	$	(48.3	)	$	—		$	(67.7	)
Benefit from (provision for) income taxes	1.1			9.3			(22.3		)	—			(12.0		)
Net loss before equity in losses from subsidiaries	$	(1.0	)	$	(8.1	)	$	(70.6	)	$	—		$	(79.7	)
Equity in losses from subsidiaries, net of tax	(78.1		)	—			—			78.1			—
Net (loss) income	$	(79.1	)	$	(8.1	)	$	(70.6	)	$	78.1		$	(79.7	)
Net loss attributable to non-controlling interests	—			—			(0.6		)	—			(0.6		)
Net (loss) income attributable to MasTec, Inc.	$	(79.1	)	$	(8.1	)	$	(70.0	)	$	78.1		$	(79.1	)
Comprehensive (loss) income	$	(117.5	)	$	(8.1	)	$	(109.0	)	$	116.5		$	(118.1	)

Condensed Consolidating Balance Sheets

CONDENSED CONSOLIDATING BALANCE SHEETS (in millions)



As of December 31, 2017	MasTec, Inc.		Guarantor Subsidiaries		Non-Guarantor Subsidiaries		Eliminations			Consolidated MasTec, Inc.
Assets
Total current assets	$	—	$	1,536.6	$	332.9	$	(17.1	)	$	1,852.4
Property and equipment, net	—		638.7		67.8		—			706.5
Goodwill and other intangible assets, net	—		1,187.9		141.0		—			1,328.9
Investments in and advances to consolidated affiliates, net	1,415.0		847.7		746.6		(3,009.3		)	—
Other long-term assets	15.8		23.4		139.6		—			178.8
Total assets	$	1,430.8	$	4,234.3	$	1,427.9	$	(3,026.4	)	$	4,066.6
Liabilities and equity
Total current liabilities	$	—	$	778.6	$	202.3	$	(17.1	)	$	963.8
Long-term debt	—		1,269.4		11.3		—			1,280.7
Other long-term liabilities	—		379.9		8.8		—			388.7
Total liabilities	$	—	$	2,427.9	$	222.4	$	(17.1	)	$	2,633.2
Total equity	$	1,430.8	$	1,806.4	$	1,205.5	$	(3,009.3	)	$	1,433.4
Total liabilities and equity	$	1,430.8	$	4,234.3	$	1,427.9	$	(3,026.4	)	$	4,066.6



As of December 31, 2016	MasTec, Inc.		Guarantor Subsidiaries		Non-Guarantor Subsidiaries		Eliminations			Consolidated MasTec, Inc.
Assets
Total current assets	$	—	$	1,257.2	$	155.5	$	(10.2	)	$	1,402.5
Property and equipment, net	—		463.7		85.4		—			549.1
Goodwill and other intangible assets, net	—		1,037.4		138.2		—			1,175.6
Investments in and advances to consolidated affiliates, net	1,083.9		617.4		867.7		(2,569.0		)	—
Other long-term assets	12.6		25.2		18.1		—			55.9
Total assets	$	1,096.5	$	3,400.9	$	1,264.9	$	(2,579.2	)	$	3,183.1
Liabilities and equity
Total current liabilities	$	—	$	742.8	$	107.4	$	(10.2	)	$	840.0
Long-term debt	—		941.7		19.7		—			961.4
Other long-term liabilities	—		258.1		20.0		—			278.1
Total liabilities	$	—	$	1,942.6	$	147.1	$	(10.2	)	$	2,079.5
Total equity	$	1,096.5	$	1,458.3	$	1,117.8	$	(2,569.0	)	$	1,103.6
Total liabilities and equity	$	1,096.5	$	3,400.9	$	1,264.9	$	(2,579.2	)	$	3,183.1

Condensed Consolidating Statements of Cash Flows

CONDENSED CONSOLIDATING STATEMENTS OF CASH FLOWS (in millions)



For the Year Ended December 31, 2017	MasTec, Inc.			Guarantor Subsidiaries			Non-Guarantor Subsidiaries			Eliminations		Consolidated MasTec, Inc.
Net cash provided by operating activities	$	—		$	155.1		$	1.2		$	—	$	156.3
Cash flows from investing activities:
Cash paid for acquisitions, net of cash acquired	—			(116.0		)	—			—		(116.0		)
Capital expenditures	—			(120.1		)	(3.3		)	—		(123.4		)
Proceeds from sale of property and equipment	—			18.2			1.8			—		20.0
Payments for other investments	—			(3.8		)	(73.3		)	—		(77.1		)
Proceeds from other investments	—			1.2			22.6			—		23.8
Net cash used in investing activities	$	—		$	(220.5	)	$	(52.2	)	$	—	$	(272.7	)
Cash flows from financing activities:
Proceeds from credit facilities	—			2,674.4			24.6			—		2,699.0
Repayments of credit facilities	—			(2,428.9		)	(28.4		)	—		(2,457.3		)
Repayments of other borrowings and capital lease obligations, net	—			(61.5		)	(9.6		)	—		(71.1		)
Payments of acquisition-related contingent consideration	—			(18.8		)	—			—		(18.8		)
Payments to non-controlling interests, including acquisition of interests and distributions	—			(22.7		)	—			—		(22.7		)
Payments for stock-based awards, net	(3.1		)	—			—			—		(3.1		)
Repurchase of common stock	(1.6		)	—			—			—		(1.6		)
Other financing activities, net	—			(6.3		)	—			—		(6.3		)
Net financing activities and advances from (to) consolidated affiliates	4.7			(89.6		)	84.9			—		—
Net cash provided by financing activities	$	—		$	46.6		$	71.5		$	—	$	118.2
Effect of currency translation on cash	—			—			(0.1		)	—		(0.1		)
Net (decrease) increase in cash and cash equivalents	$	—		$	(18.8	)	$	20.4		$	—	$	1.6
Cash and cash equivalents - beginning of period	—			28.9			9.9			—		38.8
Cash and cash equivalents - end of period	$	—		$	10.1		$	30.3		$	—	$	40.3



For the Year Ended December 31, 2016	MasTec, Inc.			Guarantor Subsidiaries			Non-Guarantor Subsidiaries			Eliminations		Consolidated MasTec, Inc.
Net cash provided by operating activities	$	—		$	130.5		$	75.1		$	—	$	205.6
Cash flows from investing activities:
Cash paid for acquisitions, net of cash acquired	—			(4.1		)	—			—		(4.1		)
Capital expenditures	—			(112.6		)	(4.5		)	—		(117.1		)
Proceeds from sale of property and equipment	—			7.6			3.6			—		11.2
Payments for other investments	—			(3.9		)	(28.2		)	—		(32.2		)
Proceeds from other investments	—			—			1.1			—		1.1
Net cash used in investing activities	$	—		$	(113.0	)	$	(28.0	)	$	—	$	(141.0	)
Cash flows from financing activities:
Proceeds from credit facilities	—			1,553.4			128.0			—		1,681.4
Repayments of credit facilities	—			(1,496.6		)	(130.5		)	—		(1,627.1		)
Repayments of other borrowings and capital lease obligations, net	—			(50.4		)	(18.3		)	—		(68.7		)
Payments of acquisition-related contingent consideration	—			(16.6		)	(3.2		)	—		(19.8		)
Proceeds from stock-based awards, net	4.2			—			—			—		4.2
Other financing activities, net	0.1			0.4			—			—		0.5
Net financing activities and advances (to) from consolidated affiliates	(4.3		)	16.4			(12.1		)	—		—
Net cash provided by (used in) financing activities	$	—		$	6.6		$	(36.1	)	$	—	$	(29.5	)
Effect of currency translation on cash	—			—			(1.3		)	—		(1.3		)
Net increase in cash and cash equivalents	$	—		$	24.1		$	9.7		$	—	$	33.8
Cash and cash equivalents - beginning of period	—			4.8			0.2			—		5.0
Cash and cash equivalents - end of period	$	—		$	28.9		$	9.9		$	—	$	38.8

CONDENSED CONSOLIDATING STATEMENTS OF CASH FLOWS (in millions)



For the Year Ended December 31, 2015	MasTec, Inc.			Guarantor Subsidiaries			Non-Guarantor Subsidiaries			Eliminations		Consolidated MasTec, Inc.
Net cash provided by operating activities	$	0.9		$	358.5		$	8.0		$	—	$	367.4
Cash flows from investing activities:
Cash paid for acquisitions, net of cash acquired	—			(0.1		)	—			—		(0.1		)
Capital expenditures	—			(71.9		)	(12.5		)	—		(84.4		)
Proceeds from sale of property and equipment	—			10.5			3.4			—		13.9
Payments for other investments	(1.9		)	—			(125.6		)	—		(127.5		)
Proceeds from other investments	—			—			69.4			—		69.4
Net cash used in investing activities	$	(1.9	)	$	(61.5	)	$	(65.3	)	$	—	$	(128.7	)
Cash flows from financing activities:
Proceeds from credit facilities	—			1,097.3			605.1			—		1,702.4
Repayments of credit facilities	—			(1,154.3		)	(587.8		)	—		(1,742.1		)
Repayments of other borrowings and capital lease obligations, net	—			(54.3		)	(16.6		)	—		(70.9		)
Repurchase of common stock	(100.0		)	—			—			—		(100.0		)
Payments of acquisition-related contingent consideration	—			(37.3		)	(10.2		)	—		(47.5		)
Proceeds from (payments for) stock-based awards, net	2.7			(1.1		)	—			—		1.6
Other financing activities, net	—			(2.4		)	—			—		(2.4		)
Net financing activities and advances from (to) consolidated affiliates	98.3			(158.6		)	60.3			—		—
Net cash provided by (used in) financing activities	$	1.0		$	(310.7	)	$	50.8		$	—	$	(258.9	)
Effect of currency translation on cash	—			—			1.1			—		1.1
Net decrease in cash and cash equivalents	$	—		$	(13.7	)	$	(5.4	)	$	—	$	(19.1	)
Cash and cash equivalents - beginning of period	—			18.5			5.6			—		24.1
Cash and cash equivalents - end of period	$	—		$	4.8		$	0.2		$	—	$	5.0

Business, Basis of Presentation and Significant Accounting Policies (Narrative) (Details) $ in Thousands	12 Months Ended
	Dec. 31, 2017 USD ($) segment	Dec. 31, 2016 USD ($)	Dec. 31, 2015 USD ($)	Dec. 31, 2014 USD ($)
Business, Basis Of Presentation And Significant Accounting Policies [Line Items]
Number of reportable segments \| segment	5
Cash	$ 40,326	$ 38,767	$ 4,984	$ 24,059
Book overdrafts	30,000	39,900
Inventory obsolescence reserves	7,700	3,500
Financing costs incurred	6,300		2,400
Deferred financing costs, net of accumulated amortization	13,000	9,800
Self-Insurance [Member] \| Workers' Compensation Policy [Member]
Business, Basis Of Presentation And Significant Accounting Policies [Line Items]
Per claim deductible, insurance policies	1,500
Self-Insurance [Member] \| General Liability Policy [Member]
Business, Basis Of Presentation And Significant Accounting Policies [Line Items]
Per claim deductible, insurance policies	3,000
Self-Insurance [Member] \| Property Insurance Policy [Member] \| Automobiles [Member]
Business, Basis Of Presentation And Significant Accounting Policies [Line Items]
Per claim deductible, insurance policies	3,000
Self-Insurance [Member] \| Umbrella Policy [Member]
Business, Basis Of Presentation And Significant Accounting Policies [Line Items]
Maximum annual coverage limit, per claim	100,000
Maximum annual coverage limit, in aggregate	100,000
Self-Insurance [Member] \| Employee Group Medical Claims Policy [Member]
Business, Basis Of Presentation And Significant Accounting Policies [Line Items]
Loss contingency, maximum loss per employee	500
Interest Expense [Member]
Business, Basis Of Presentation And Significant Accounting Policies [Line Items]
Amortization of deferred financing costs	3,300	3,200	$ 2,900
2017 Acquisitions [Member]
Business, Basis Of Presentation And Significant Accounting Policies [Line Items]
Goodwill, measurement period adjustments	2,700
Proportionately Consolidated Joint Ventures [Member]
Business, Basis Of Presentation And Significant Accounting Policies [Line Items]
Cash	$ 17,300	$ 7,700

Business, Basis of Presentation and Significant Accounting Policies (Revenue Recognition) (Narrative) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Revenue [Line Items]
Unapproved change orders, description	The Company may incur costs subject to change orders, whether approved or unapproved by the customer, and/or claims related to certain contracts. Management determines the probability that such costs will be recovered based upon engineering studies and legal opinions, past practices with the customer, specific discussions, correspondence or preliminary negotiations with the customer. The Company treats such costs as a cost of contract performance in the period incurred if it is not probable that the costs will be recovered, and defers costs or recognizes revenue up to the amount of the related cost if it is probable that the contract price will be adjusted and can be reliably estimated. As of December 31, 2017 and 2016, the Company had approximately $146 million and $17 million, respectively, of change orders and/or claims that had been included as contract price adjustments on certain contracts that were in the process of being resolved in the normal course of business, including through negotiation, arbitration and other proceedings. These contract price adjustments, which are included within costs and earnings in excess of billings or billed accounts receivable, as appropriate, represent management’s best estimate of contract revenue that has been earned and that management believes is probable of collection.
Unbilled Revenues [Member]
Revenue [Line Items]
Unapproved change orders, contract revenue recognized (in dollars)	$ 142	$ 4
Accounts Receivable [Member]
Revenue [Line Items]
Unapproved change orders, expected to be billed and collected within one year, amount (in dollars)	$ 146	$ 17
Maximum [Member]
Revenue [Line Items]
Fixed price contracts, percentage-of-completion method, term within which generally completed (in years)	1 year
Change order approval process, term within which expected to be completed (in years)	1 year
Contracts Accounted for under Percentage-of-Completion [Member] \| Maximum [Member]
Revenue [Line Items]
Change in accounting estimate, percentage-of-completion projects, financial effect on project profit, percentage	5.00%	5.00%
Revenue [Member] \| Master Service and Other Service Agreements [Member] \| Concentration Risk from Type of Arrangement [Member]
Revenue [Line Items]
Concentration risk, percentage of total	36.00%	43.00%	48.00%

Business, Basis of Presentation and Significant Accounting Policies (Goodwill and Indefinite-Lived Intangible Assets) (Narrative) (Details) $ in Thousands	12 Months Ended
	Dec. 31, 2017 USD ($)	Dec. 31, 2016 USD ($)	Dec. 31, 2015 USD ($)
Goodwill and Indefinite-Lived Intangible Assets [Line Items]
Goodwill impairment testing, number of reporting units			4
Goodwill, carrying amount (in dollars)	$ 1,137,738	$ 995,874	$ 988,500
Pre-Qualifications [Member]
Goodwill and Indefinite-Lived Intangible Assets [Line Items]
Indefinite-lived intangible assets, carrying amount (in dollars)	77,600	74,600	73,400
Trade Names [Member]
Goodwill and Indefinite-Lived Intangible Assets [Line Items]
Indefinite-lived intangible assets, carrying amount (in dollars)	$ 34,500	$ 34,500	$ 34,800
Goodwill [Member]
Goodwill and Indefinite-Lived Intangible Assets [Line Items]
Fair value measurements, valuation techniques	Management estimated their respective fair values using a combination of market and income approaches. Under the market approach, fair values were estimated using published market multiples for comparable companies. Under the income approach, a discounted cash flow methodology was used, including: (i) management estimates, such as projections of revenue, operating costs and cash flows, taking into consideration historical and anticipated financial results; (ii) general economic and market conditions; and (iii) the impact of planned business and operational strategies. Estimated discount rates were determined using the Company’s average cost of capital at the time of the analysis, taking into consideration the risks inherent within each reporting unit individually, which are greater than the risks inherent in the Company as a whole.
Impairment testing, significant assumptions	In 2017, significant assumptions used in testing the reporting units included terminal values based on a terminal growth rate of 3.5%, five to nine years of discounted cash flows prior to the terminal value, and discount rates ranging from 13.0% to 15.5%.
Goodwill impairment testing, terminal growth rate (percentage)	3.50%
Impairment testing, number of years of discounted cash flows before terminal value		9 years	9 years
Impairment testing, discount rate sensitivity analysis, spread on discount rate for which evaluation was completed (percentage)			1.00%
Goodwill [Member] \| Minimum [Member]
Goodwill and Indefinite-Lived Intangible Assets [Line Items]
Goodwill impairment testing, terminal growth rate (percentage)		3.00%	3.00%
Impairment testing, number of years of discounted cash flows before terminal value	5 years
Impairment testing, discount rate (percentage)	13.00%	13.00%	12.00%
Goodwill [Member] \| Maximum [Member]
Goodwill and Indefinite-Lived Intangible Assets [Line Items]
Goodwill impairment testing, terminal growth rate (percentage)		3.50%	3.50%
Impairment testing, number of years of discounted cash flows before terminal value	9 years
Impairment testing, discount rate (percentage)	15.50%	14.50%	14.00%
Indefinite-Lived Intangible Assets [Member] \| Pre-Qualifications [Member]
Goodwill and Indefinite-Lived Intangible Assets [Line Items]
Impairment testing, significant assumptions	Management estimated the fair values of these intangible assets using a cost methodology, incorporating estimates of the opportunity cost associated with the assets’ loss based on discounted cash flows over a two to four-year period. The impairment tests incorporated estimated discount rates ranging from 13.0% to 14.0%.
Indefinite-Lived Intangible Assets [Member] \| Minimum [Member] \| Pre-Qualifications [Member]
Goodwill and Indefinite-Lived Intangible Assets [Line Items]
Impairment testing, number of years of discounted cash flows before terminal value	2 years	2 years	2 years
Impairment testing, discount rate (percentage)	13.00%	13.00%	12.00%
Indefinite-Lived Intangible Assets [Member] \| Maximum [Member] \| Pre-Qualifications [Member]
Goodwill and Indefinite-Lived Intangible Assets [Line Items]
Impairment testing, number of years of discounted cash flows before terminal value	4 years	3 years	3 years
Impairment testing, discount rate (percentage)	14.00%	13.50%	14.00%
Power Generation and Industrial [Member]
Goodwill and Indefinite-Lived Intangible Assets [Line Items]
Number of reporting unit(s) which comprise(s) more than one component	1
Number of aggregated components in reporting unit	2	1	1
Goodwill impairment testing, number of reporting units	1
Goodwill, carrying amount (in dollars)	$ 135,800	$ 117,600	$ 117,600
Power Generation and Industrial [Member] \| Indefinite-Lived Intangible Assets [Member] \| Trade Names [Member]
Goodwill and Indefinite-Lived Intangible Assets [Line Items]
Impairment testing, significant assumptions	Management estimated the fair value of the intangible asset using an income approach, incorporating estimates of discounted cash flows over a five-year period prior to the terminal value. The impairment test incorporated an estimated discount rate of 14%.
Impairment testing, number of years of discounted cash flows before terminal value	5 years
Impairment testing, discount rate (percentage)	14.00%
Oil and Gas [Member]
Goodwill and Indefinite-Lived Intangible Assets [Line Items]
Number of aggregated components in reporting unit	1	1	1
Goodwill impairment testing, number of reporting units	2	2	3
Goodwill, carrying amount (in dollars)	$ 385,600	$ 307,700	$ 306,100
Oil and Gas [Member] \| Pre-Qualifications [Member]
Goodwill and Indefinite-Lived Intangible Assets [Line Items]
Indefinite-lived intangible asset impairment testing, number of indefinite-lived intangible assets			2
Oil and Gas [Member] \| Reporting Unit or Intangible, Quantitative Testing, Estimated Fair Value Not Substantially Exceeding Carrying Value [Member]
Goodwill and Indefinite-Lived Intangible Assets [Line Items]
Goodwill impairment testing, number of reporting units	2	1
Goodwill, carrying amount (in dollars)		$ 15,000
Goodwill impairment testing, reporting unit, percentage of estimated fair value in excess of carrying value		11.00%
Oil and Gas [Member] \| Reporting Unit or Intangible, Quantitative Testing, Estimated Fair Value Not Substantially Exceeding Carrying Value [Member] \| Pre-Qualifications [Member]
Goodwill and Indefinite-Lived Intangible Assets [Line Items]
Indefinite-lived intangible assets, carrying amount (in dollars)	$ 45,000
Indefinite-lived intangible assets impairment testing, percentage of estimated fair value in excess of carrying value	19.00%
Oil and Gas [Member] \| Reporting Unit A Quantitative Testing, Estimated Fair Value Not Substantially Exceeding Carrying Value [Member]
Goodwill and Indefinite-Lived Intangible Assets [Line Items]
Goodwill, carrying amount (in dollars)	$ 65,000
Goodwill impairment testing, reporting unit, percentage of estimated fair value in excess of carrying value	10.00%
Oil and Gas [Member] \| Reporting Unit B Quantitative Testing, Estimated Fair Value Not Substantially Exceeding Carrying Value [Member]
Goodwill and Indefinite-Lived Intangible Assets [Line Items]
Goodwill, carrying amount (in dollars)	$ 15,000
Goodwill impairment testing, reporting unit, percentage of estimated fair value in excess of carrying value	19.00%
Oil and Gas [Member] \| Reporting Unit or Intangible, Quantitative Testing, Impairment Charge Recorded [Member]
Goodwill and Indefinite-Lived Intangible Assets [Line Items]
Goodwill impairment testing, number of reporting units			1
Goodwill, carrying amount (in dollars)			$ 11,200
Goodwill, pre-tax impairment charge (in dollars)			68,500
Oil and Gas [Member] \| Reporting Unit or Intangible, Quantitative Testing, Impairment Charge Recorded [Member] \| Pre-Qualifications [Member]
Goodwill and Indefinite-Lived Intangible Assets [Line Items]
Indefinite-lived intangible assets, carrying amount (in dollars)			$ 20,500
Indefinite-lived intangible asset impairment testing, number of indefinite-lived intangible assets			1
Indefinite-lived intangible assets, pre-tax impairment charge (in dollars)			$ 10,100
Oil and Gas [Member] \| Goodwill [Member] \| Reporting Unit or Intangible, Quantitative Testing, Estimated Fair Value Not Substantially Exceeding Carrying Value [Member]
Goodwill and Indefinite-Lived Intangible Assets [Line Items]
Impairment testing, sensitivity analysis, description	A 100 basis point increase in the discount rate would not have resulted in the reporting units’ carrying values exceeding their fair values.
Impairment testing, discount rate sensitivity analysis, spread on discount rate for which evaluation was completed (percentage)	1.00%	1.00%
Oil and Gas [Member] \| Indefinite-Lived Intangible Assets [Member] \| Reporting Unit or Intangible, Quantitative Testing, Estimated Fair Value Not Substantially Exceeding Carrying Value [Member] \| Pre-Qualifications [Member]
Goodwill and Indefinite-Lived Intangible Assets [Line Items]
Impairment testing, sensitivity analysis, description	a 100 basis point increase in the discount rate would not have resulted in this asset’s carrying value exceeding its fair value.
Impairment testing, discount rate sensitivity analysis, spread on discount rate for which evaluation was completed (percentage)	1.00%
Communications [Member]
Goodwill and Indefinite-Lived Intangible Assets [Line Items]
Number of aggregated components in reporting unit	1	1	1
Goodwill, carrying amount (in dollars)	$ 466,400	$ 420,700	$ 414,900
Electrical Transmission [Member]
Goodwill and Indefinite-Lived Intangible Assets [Line Items]
Goodwill, carrying amount (in dollars)	$ 149,900	$ 149,900	$ 149,900
Goodwill impairment testing, reporting unit, percentage of estimated fair value in excess of carrying value		5.00%	5.00%
Electrical Transmission [Member] \| Pre-Qualifications [Member]
Goodwill and Indefinite-Lived Intangible Assets [Line Items]
Indefinite-lived intangible asset impairment testing, number of indefinite-lived intangible assets			1
Electrical Transmission [Member] \| Goodwill [Member]
Goodwill and Indefinite-Lived Intangible Assets [Line Items]
Impairment testing, discount rate sensitivity analysis, spread on discount rate for which evaluation was completed (percentage)		1.00%	1.00%
Other [Member]
Goodwill and Indefinite-Lived Intangible Assets [Line Items]
Number of aggregated components in reporting unit	1	1	1

Business, Basisi of Presentation and Significant Accounting Policies (Income Taxes) (Narrative) (Details) - USD ($)	3 Months Ended	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Subsequent Event [Line Items]
U.S. corporate tax rate, percent			35.00%	35.00%	35.00%
Change in enacted tax rate, non-cash tax benefit (in dollars)	$ 120,100,000		$ 120,100,000
Provision for U.S. income taxes on unremitted foreign earnings	$ 0		$ 0
Subsequent Event [Member]
Subsequent Event [Line Items]
U.S. corporate tax rate, percent		21.00%

Business, Basis of Presentation and Significant Accounting Policies (Stock-Based Compensation) (Narrative) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock-based compensation, shares withheld for the exercise prices of options and/or employee tax withholdings (in shares)	138,519	44,988	74,407
Stock-based compensation, payments for employee tax obligations to taxing authorities (in dollars)	$ 6.2	$ 0.6	$ 1.1
Restricted Shares [Member] \| Maximum [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock-based compensation, vesting period (in years)	3 years
Employee Stock Purchase Plans [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock-based compensation plan, description	The Company has certain employee stock purchase plans under which shares of the Company’s common stock are available for purchase by eligible employees. These plans allow qualified employees to purchase MasTec, Inc. common stock at 85% of its fair market value at the lower of (i) the date of commencement of the offering period or (ii) the last day of the exercise period, as defined in the plan documents.
Stock-based compensation, purchase price of common stock, percentage	85.00%
Stock-based compensation, fair value assumptions, method used	The fair value of purchases under the Company’s employee stock purchase plans is estimated using the Black-Scholes option-pricing valuation model.
Fair value measurements, significant assumptions	The determination of fair value of stock-based awards using an option-pricing model is affected by the Company’s stock price as well as assumptions pertaining to several variables, including expected stock price volatility, the expected term of the award and the risk-free rate of interest. In the option-pricing model for the Company’s employee stock purchase plans, expected stock price volatility is based on historical volatility of the Company’s common stock. The expected term of the award is based on historical and expected exercise patterns and the risk-free rate of interest is based on U.S. Treasury yields. The Company has not paid dividends in the past, and does not anticipate paying dividends in the foreseeable future, and therefore uses an expected dividend yield of zero.
Stock-based compensation, fair value assumptions, expected dividend yield (percentage)	0.00%

Business, Basis of Presentation and Significant Accounting Policies (Restructuring Activities) (Narrative) (Details) - USD ($) $ in Thousands	3 Months Ended				12 Months Ended
	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2016	Dec. 31, 2017
Restructuring Activities [Line Items]
Restructuring charges	$ 1,400	$ 4,700	$ 5,100	$ 4,100
Restructuring liabilities, current	5,700				$ 5,700	$ 2,200
Other current assets	55,109				55,109	$ 35,763
Held-for-Sale [Member]
Restructuring Activities [Line Items]
Other current assets	$ 1,100				1,100
General and Administrative Expenses [Member]
Restructuring Activities [Line Items]
Restructuring charges					12,300
Other Expense [Member]
Restructuring Activities [Line Items]
Restructuring charges					$ 2,900

Business, Basis of Presentation and Significant Accounting Policies (New Accounting Pronouncements) (Narrative) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Backlog, expected timing of revenue recognition, period (in months)	18 months
Payments for acquisition-related contingent consideration, financing activities	$ 18,843	$ 19,822	$ 47,523
ASU 2016-15 [Member] \| Reclassification Adjustment [Member]
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Payments for acquisition-related contingent consideration, operating activities	12,000
Payments for acquisition-related contingent consideration, financing activities	$ (12,000)

Earnings Per Share (Narrative) (Details) - shares shares in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Earnings Per Share [Line Items]
Earnings per share reconciliation disclosure, methodology	Basic earnings or loss per share is computed by dividing net income or loss attributable to MasTec by the weighted average number of common shares outstanding for the period, which excludes non-participating unvested restricted share awards. Diluted earnings per share is computed by dividing net income or loss attributable to MasTec by the weighted average number of fully diluted shares, as calculated under the treasury stock method, which includes the potential effect of dilutive common stock equivalents, such as issued but unvested restricted shares. If the Company reports a loss, rather than income, the computation of diluted loss per share excludes the effect of dilutive common stock equivalents, as their effect would be anti-dilutive.
Dilutive common stock equivalents (in shares)	1,422	1,022	0
ASU 2016-09 [Member]
Earnings Per Share [Line Items]
Dilutive common stock equivalents (in shares)	300

Earnings Per Share (Schedule of Earnings Per Share Information) (Details) - USD ($)
shares in Thousands, $ in Thousands

3 Months Ended

12 Months Ended

Dec. 31, 2017

Sep. 30, 2017

Jun. 30, 2017

Mar. 31, 2017

Dec. 31, 2016

Sep. 30, 2016

Jun. 30, 2016

Mar. 31, 2016

Dec. 31, 2017

Dec. 31, 2016

Dec. 31, 2015

Net income (loss) attributable to MasTec:

Net income (loss) - basic (in dollars)

$ 160,800

$ 63,800

$ 81,700

$ 41,000

$ 53,600

$ 56,300

$ 24,100

$ (2,700)

$ 347,213

^[1]

$ 131,263

^[1]

$ (79,110)

^[1]

Net income (loss) - diluted (in dollars)

$ 347,213

$ 131,263

$ (79,110)

Weighted average shares outstanding:

Weighted average shares outstanding - basic

80,903

80,372

80,489

Dilutive common stock equivalents (in shares)

1,422

1,022

Weighted average shares outstanding - diluted

82,325

81,394

80,489

Common Stock [Member]

Additional information:

Weighted average anti-dilutive common stock equivalents (in shares)

^[2]

564

[1]	Calculated as total net income (loss) less amounts attributable to non-controlling interests.
[2]	For the year ended December 31, 2016, represents anti-dilutive common stock equivalents as calculated under the treasury stock method, and, for the year ended December 31, 2015, represents anti-dilutive common stock equivalents due to the Company having reported a net loss.

Goodwill and Other Intangible Assets (Rollforward of Goodwill by Segment) (Details) - USD ($)
$ in Thousands

12 Months Ended

Dec. 31, 2017

Dec. 31, 2016

Dec. 31, 2015

$ 1,212,500

$ 1,057,000

^[1]

(74,800)

(68,500)

995,874

$ 988,500

138,000

3,800

1,600

Earn-Out Liabilities [Member]

1,137,738

995,874

Accruals of acquisition-related contingent consideration, net

^[2]

5,800

Communications [Member]

466,400

414,900

^[1]

420,700

414,900

45,700

Communications [Member] | Earn-Out Liabilities [Member]

466,400

420,700

Accruals of acquisition-related contingent consideration, net

^[2]

5,800

Oil and Gas [Member]

460,400

374,600

^[1]

(74,800)

(68,500)

307,700

306,100

74,100

3,800

1,600

Oil and Gas [Member] | Earn-Out Liabilities [Member]

385,600

307,700

Accruals of acquisition-related contingent consideration, net

^[2]

Electrical Transmission [Member]

149,900

^[1]

149,900

Electrical Transmission [Member] | Earn-Out Liabilities [Member]

149,900

Accruals of acquisition-related contingent consideration, net

^[2]

Power Generation and Industrial [Member]

135,800

117,600

^[1]

$ 0

117,600

18,200

Power Generation and Industrial [Member] | Earn-Out Liabilities [Member]

$ 135,800

117,600

Accruals of acquisition-related contingent consideration, net

^[2]

$ 0

[1]	Accumulated impairment losses include the effect of currency translation gains and/or losses.
[2]	Represents contingent consideration for acquisitions prior to January 1, 2009, which is accrued as incurred, in accordance with U.S. GAAP.

Goodwill and Other Intangible Assets (Rollforward of Other Intangible Assets) (Details) - USD ($)
$ in Thousands

12 Months Ended

Dec. 31, 2017

Dec. 31, 2016

Dec. 31, 2015

Other intangible assets, gross carrying amount

$ 329,300

Accumulated amortization

(129,900)

Other intangible assets, net, beginning balance

$ 179,711

$ 199,400

Amortization expense

(20,900)

(21,300)

(28,400)

3,500

1,600

Additions from new business combinations, intangible assets

28,800

Other intangible assets, net, amortizing, ending balance

$ 79,000

79,000

Other intangible assets, net, ending balance

$ 191,142

191,142

179,711

199,400

Weighted Average [Member]

Remaining weighted average amortization period (in years)

9 years

Customer Relationships and Backlog [Member]

Other intangible assets, amortizing, gross carrying amount

195,400

Accumulated amortization

(114,600)

Other intangible assets, net, amortizing, beginning balance

63,200

80,800

Amortization expense

(19,300)

(17,900)

Currency translation adjustments, amortizing intangible assets

400

300

Additions from new business combinations, amortizing intangible assets

26,300

Other intangible assets, net, amortizing, ending balance

$ 70,600

70,600

63,200

80,800

Customer Relationships and Backlog [Member] | Weighted Average [Member]

Remaining weighted average amortization period (in years)

9 years

Other Amortizing Intangible Assets [Member]

Other intangible assets, amortizing, gross carrying amount

^[1]

25,700

Accumulated amortization

^[1]

(15,300)

Other intangible assets, net, amortizing, beginning balance

^[1]

7,400

10,400

Amortization expense

^[1]

(1,600)

(3,400)

Currency translation adjustments, amortizing intangible assets

^[1]

100

Additions from new business combinations, amortizing intangible assets

^[1]

300

2,500

Other intangible assets, net, amortizing, ending balance

^[1]

$ 8,400

8,400

7,400

10,400

Other Amortizing Intangible Assets [Member] | Weighted Average [Member]

Remaining weighted average amortization period (in years)

^[1]

8 years

Trade Names [Member]

Other intangible assets, non-amortizing, beginning balance

34,500

34,800

Other intangible assets, non-amortizing, beginning balance

34,500

34,800

Currency translation adjustments, non-amortizing intangible assets

Additions from new business combinations, non-amortizing intangible assets

(300)

Other intangible assets, non-amortizing, ending balance

$ 34,500

34,500

34,800

Pre-Qualifications [Member]

Other intangible assets, non-amortizing, beginning balance

74,600

73,400

Other intangible assets, non-amortizing, beginning balance

74,600

73,400

Currency translation adjustments, non-amortizing intangible assets

3,000

1,200

Additions from new business combinations, non-amortizing intangible assets

Other intangible assets, non-amortizing, ending balance

$ 77,600

$ 74,600

$ 73,400

[1]	Consists principally of trade names and non-compete agreements.

Goodwill and Other Intangible Assets (Narrative) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Goodwill and Intangible Assets Disclosure [Abstract]
Amortization expense, intangible assets	$ 20.9	$ 21.3	$ 28.4

Goodwill and Other Intangible Assets (Schedule of Expected Future Amortization Expense) (Details) $ in Millions	Dec. 31, 2017 USD ($)
Amortization Expense
Intangible assets, expected future amortization expense, 2018	$ 19.5
Intangible assets, expected future amortization expense, 2019	13.4
Intangible assets, expected future amortization expense, 2020	11.0
Intangible assets, expected future amortization expense, 2021	8.4
Intangible assets, expected future amortization expense, 2022	6.9
Intangible assets, expected future amortization expense, thereafter	19.8
Intangible assets, expected future amortization expense, total	$ 79.0

Goodwill and Other Intangible Assets (2017 Acquisitions) (Narrative) (Details) $ in Millions		12 Months Ended
	Dec. 31, 2017 USD ($)	Dec. 31, 2017 USD ($)	Dec. 31, 2016 USD ($)
Business Combinations [Line Items]
Business combinations, number of acquisitions		3
Business combinations, unaudited pro forma revenue (in dollars)		$ 6,680.2	$ 5,320.1
Business combinations, unaudited pro forma net income (in dollars)		$ 354.9	$ 140.0
Business combinations, unaudited pro forma information, description		The above indicated unaudited pro forma financial results, which represent the results of operations of the companies acquired as if the acquired companies had been consolidated as of January 1, 2016, are provided for illustrative purposes only and do not purport to be indicative of the actual results that would have been achieved by the combined companies for the periods indicated, or of the results that may be achieved by the combined companies in the future. The unaudited supplemental pro forma financial results have been prepared by adjusting the historical results of MasTec to include the historical results of the acquired businesses described above, and then adjusted (i) to remove acquisition costs; (ii) to increase amortization expense resulting from the acquired intangible assets; (iii) to increase interest expense as a result of the cash consideration paid; (iv) to reduce interest expense from debt repaid upon acquisition; and (iv) to eliminate the effects of intercompany transactions. These unaudited supplemental pro forma financial results do not include adjustments to reflect other cost savings or synergies that may have resulted from these acquisitions.
Business combinations, consolidated acquisition-related results, revenue (in dollars)		$ 160.1
Business combinations, consolidated acquisition-related results, net income (in dollars)		$ 10.2
Earn-Out Liabilities [Member]
Business Combinations [Line Items]
Business combinations, contingent consideration liabilities, range of potential earn-out liabilities, maximum unlimited		there is no maximum payment amount
2017 Acquisitions [Member]
Business Combinations [Line Items]
Business combinations, percentage of interests acquired	100.00%	100.00%
Business combinations, acquired finite-lived intangible assets, weighted average lives (in years)		10 years
Business combinations, goodwill recognized, description		The goodwill balances for the respective acquisitions represent the estimated value of each acquired company’s geographic presence in key markets, its assembled workforce and management team industry-specific project management expertise, as well as synergies expected to be achieved from the combined operations of the acquired companies and MasTec.
Business combinations, goodwill, expected tax deductible amount (in dollars)	$ 75.0	$ 75.0
2017 Acquisitions [Member] \| Earn-Out Liabilities [Member]
Business Combinations [Line Items]
Business combinations, contingent consideration, basis for amount		The contingent consideration included in the table above equals the acquired companies’ earnings before interest, taxes, depreciation and amortization (“EBITDA”) above certain thresholds, if applicable, for a period of five years, as set forth in the respective purchase agreements, which amounts are payable annually.
Contingent consideration, earn-out period		5 years
Business combinations, contingent consideration, fair value measurements, valuation technique		The fair values of the earn-out liabilities were estimated using income approaches such as discounted cash flows or option pricing models and incorporate significant inputs not observable in the market.
Fair value measurements, significant assumptions		Key assumptions in the estimated valuations include the discount rate and probability-weighted EBITDA projections.
Business combinations, contingent consideration liabilities, range of potential undiscounted earn-out liabilities, low	9.0	$ 9.0
Business combinations, contingent consideration liabilities, range of potential undiscounted earn-out liabilities, high	$ 185.0	$ 185.0
Business combinations, contingent consideration liabilities, range of potential earn-out liabilities, maximum unlimited		there is no maximum payment amount
2017 Acquisitions [Member] \| Customer Relationships [Member]
Business Combinations [Line Items]
Business combinations, acquired finite-lived intangible assets, weighted average lives (in years)	11 years
2017 Acquisitions [Member] \| Backlog [Member]
Business Combinations [Line Items]
Business combinations, acquired finite-lived intangible assets, weighted average lives (in years)	4 years
2017 Acquisitions [Member] \| Other Amortizing Intangible Assets [Member]
Business Combinations [Line Items]
Business combinations, acquired finite-lived intangible assets, weighted average lives (in years)	7 years
2017 Communications Acquisition [Member]
Business Combinations [Line Items]
Business combinations, description of acquired entity		a wireline/fiber deployment construction contractor
2017 Power Generation and Industrial Acquisition [Member]
Business Combinations [Line Items]
Business combinations, description of acquired entity		a heavy civil construction services company
2017 Oil and Gas Acquisition [Member]
Business Combinations [Line Items]
Business combinations, description of acquired entity		an oil and gas pipeline equipment company

Goodwill and Other Intangible Assets (Schedule of Consideration Paid and Net Assets Acquired, Business Combinations) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Identifiable assets acquired and liabilities assumed:
Goodwill	$ 1,137,738	$ 995,874	$ 988,500
Earn-Out Liabilities [Member]
Acquisition consideration:
Fair value of contingent consideration (earn-out liability)	102,534	$ 0	$ 0
2017 Acquisitions [Member]
Acquisition consideration:
Cash	117,900
Total consideration transferred	211,400
Identifiable assets acquired and liabilities assumed:
Current assets, primarily composed of accounts receivable and $2.8 million of cash acquired	42,700
Cash acquired	2,800
Property and equipment	56,700
Amortizing intangible assets	28,800
Other long-term assets	500
Current liabilities, including current portion of capital lease obligations and long-term debt	(29,200)
Long-term debt, including capital lease obligations	(9,900)
Deferred income taxes	(16,200)
Total identifiable net assets	73,400
Goodwill	138,000
Total net assets acquired, including goodwill	211,400
2017 Acquisitions [Member] \| Earn-Out Liabilities [Member]
Acquisition consideration:
Fair value of contingent consideration (earn-out liability)	$ 93,500

Fair Value of Financial Instruments (Assets and Liabilities Measured at Fair Value on a Recurring Basis) (Narrative) (Details) - Earn-Out Liabilities [Member] - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Fair Value, Financial Instruments Measured on a Recurring Basis [Line Items]
Acquisition-related contingent consideration liabilities, range of potential earn-out liabilities, maximum unlimited	there is no maximum payment amount
Acquisition-related contingent consideration liabilities, additions	$ 102.5
Acquisition-related contingent consideration liabilities, payments	18.8	$ 15.8	$ 40.5
Other Income (Expense) [Member]
Fair Value, Financial Instruments Measured on a Recurring Basis [Line Items]
Acquisition-related contingent consideration liabilities, (increase) reduction, (loss) gain included in earnings	12.3	(2.7)	20.1
Foreign Currency Translation Adjustments [Member]
Fair Value, Financial Instruments Measured on a Recurring Basis [Line Items]
Acquisition-related contingent consideration liabilities, foreign currency translation gains			8.0
Level 3 [Member] \| Fair Value [Member]
Fair Value, Financial Instruments Measured on a Recurring Basis [Line Items]
Acquisition-related contingent consideration liabilities, fair value	117.2	45.8
Level 3 [Member] \| Fair Value [Member] \| Other Current Liabilities [Member]
Fair Value, Financial Instruments Measured on a Recurring Basis [Line Items]
Acquisition-related contingent consideration liabilities, fair value	$ 22.6	$ 21.8
Level 3 [Member] \| Fair Value Measurements, Recurring [Member]
Fair Value, Financial Instruments Measured on a Recurring Basis [Line Items]
Fair value measurements, valuation techniques	The fair value of the Company’s earn-out liabilities is estimated using income approaches such as discounted cash flows or option pricing models and incorporates significant inputs not observable in the market.
Fair value measurements, significant assumptions	Key assumptions include the discount rate and probability-weighted EBITDA projections.
Level 3 [Member] \| Fair Value Measurements, Recurring [Member] \| Fair Value [Member]
Fair Value, Financial Instruments Measured on a Recurring Basis [Line Items]
Acquisition-related contingent consideration liabilities, range of potential undiscounted earn-out liabilities, low	$ 22.0
Acquisition-related contingent consideration liabilities, range of potential undiscounted earn-out liabilities, high	$ 204.8
Acquisition-related contingent consideration liabilities, net increase (reduction)			(39.2)
Acquisition-related contingent consideration liabilities, reclassification amount			19.1
Reduction in receivable, amount			$ 19.1

Fair Value of Financial Instruments (Assets and Liabilities Measured at Fair Value on a Non-Recurring Basis) (Narrative) (Details) - 4.875% Senior Notes [Member] - Senior Notes [Member] - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016
Fair Value, Financial Instruments Measured on a Non-Recurring Basis [Line Items]
Debt instrument, interest rate (percentage)	4.875%
Fair Value Measurements, Non-Recurring [Member] \| Level 1 [Member]
Fair Value, Financial Instruments Measured on a Non-Recurring Basis [Line Items]
Fair value measurements, valuation techniques	the estimated fair value of the 4.875% Senior Notes, based on quoted market prices in active markets, a Level 1 input
Fair Value Measurements, Non-Recurring [Member] \| Gross Carrying Amount [Member]
Fair Value, Financial Instruments Measured on a Non-Recurring Basis [Line Items]
4.875% Senior Notes (in dollars)	$ 400.0	$ 400.0
Fair Value Measurements, Non-Recurring [Member] \| Fair Value [Member] \| Level 1 [Member]
Fair Value, Financial Instruments Measured on a Non-Recurring Basis [Line Items]
4.875% Senior Notes (in dollars)	$ 410.0	$ 388.0

Fair Value of Financial Instruments (Cost and Equity Investees) (Narrative) (Details) $ in Millions	Dec. 31, 2017 USD ($)
Fair Value, Financial Instruments Measured on a Non-Recurring Basis [Line Items]
Equity method investments, cumulative undistributed earnings	$ 16.9
Waha JVs [Member] \| Equity Investee [Member]
Fair Value, Financial Instruments Measured on a Non-Recurring Basis [Line Items]
Equity investment, ownership percentage	33.00%
CCI [Member] \| Immediate Family Member of Management [Member]
Fair Value, Financial Instruments Measured on a Non-Recurring Basis [Line Items]
Cost investment, original cost	$ 15.0

Fair Value of Financial Instruments (The Waha JVs) (Narrative) (Details)	12 Months Ended
	Dec. 31, 2017 USD ($)	Dec. 31, 2016 USD ($)	Dec. 31, 2015 USD ($)
Fair Value, Financial Instruments Measured on a Non-Recurring Basis [Line Items]
Equity in earnings (losses) of unconsolidated affiliates	$ 21,328,000	$ 3,528,000	$ (7,978,000)
Unrealized gains (losses) on equity investee activity, net of tax	475,000	3,952,000	0
Credit Facility [Member]
Fair Value, Financial Instruments Measured on a Non-Recurring Basis [Line Items]
Letters of credit issued	$ 157,100,000	314,300,000
Waha JVs [Member] \| Equity Investee [Member]
Fair Value, Financial Instruments Measured on a Non-Recurring Basis [Line Items]
Number of pipelines in operation	2
Equity investments, equity and other contributions	$ 73,000,000	27,000,000
Equity investments, net contributions			0
Net investment, equity investments	121,000,000	6,000,000
Revenue, related parties	256,100,000	245,000,000
Receivables, including retainage, net of BIEC, related parties	2,800,000	71,200,000
Waha JVs [Member] \| Equity Investee [Member] \| Interest Rate Swap [Member]
Fair Value, Financial Instruments Measured on a Non-Recurring Basis [Line Items]
Equity in earnings (losses) of unconsolidated affiliates			(4,400,000)
Unrealized gains (losses) on equity investee activity	800,000	6,400,000
Unrealized gains (losses) on equity investee activity, net of tax	500,000	4,000,000
Waha JVs [Member] \| Equity Investee [Member] \| Other [Member]
Fair Value, Financial Instruments Measured on a Non-Recurring Basis [Line Items]
Equity in earnings (losses) of unconsolidated affiliates	21,300,000		$ (4,400,000)
Waha JVs [Member] \| Equity Investee [Member] \| Credit Facility [Member] \| Commercial and/or Financial Standby [Member]
Fair Value, Financial Instruments Measured on a Non-Recurring Basis [Line Items]
Letters of credit issued	$ 19,000,000	$ 91,000,000

Fair Value of Financial Instruments (Other Investments - Pensare) (Narrative) (Details) - Pensare [Member] - Chief Executive Officer [Member] - USD ($) $ / shares in Units, $ in Millions		3 Months Ended
	Dec. 31, 2017	Sep. 30, 2017
Fair Value, Financial Instruments Measured on a Non-Recurring Basis [Line Items]
Cost method investment and warrants, amount paid (in dollars)		$ 2.0
Cost method investment, ownership percentage	4.00%
Plan [Member]
Fair Value, Financial Instruments Measured on a Non-Recurring Basis [Line Items]
Warrants, exercise price (in dollars per share)	$ 11.50
Common Stock [Member] \| Plan [Member]
Fair Value, Financial Instruments Measured on a Non-Recurring Basis [Line Items]
Investment, restriction period (in years)	1 year
Warrant [Member]
Fair Value, Financial Instruments Measured on a Non-Recurring Basis [Line Items]
Warrants, number held	2,000,000

Fair Value of Financial Instruments (Other Investments - Pacer) (Narrative) (Details) $ in Thousands	12 Months Ended
	Dec. 31, 2017 USD ($)	Dec. 31, 2016 USD ($)	Dec. 31, 2015 USD ($)	Mar. 31, 2016	Dec. 31, 2014
Fair Value, Financial Instruments Measured on a Non-Recurring Basis [Line Items]
Equity in earnings (losses) of unconsolidated affiliates	$ 21,328	$ 3,528	$ (7,978)
Pacer [Member] \| Investee [Member]
Fair Value, Financial Instruments Measured on a Non-Recurring Basis [Line Items]
Number of joint ventures					2
Construction projects, percentage complete				100.00%
Pacer [Member] \| Investee [Member] \| Canadian Dollars [Member]
Fair Value, Financial Instruments Measured on a Non-Recurring Basis [Line Items]
Other equity investee, proceeds related to ongoing liquidation	22,500
Income (expense) from investment, change in expected recovery amounts	(400)
Equity in earnings (losses) of unconsolidated affiliates		3,600
Net investment, equity investments	$ 9,600	31,400
Revenue, related parties		$ 600	$ 2,900
Pacer [Member] \| Investee [Member] \| Joint Venture Which Was Liquidated in 2016 [Member]
Fair Value, Financial Instruments Measured on a Non-Recurring Basis [Line Items]
Number of joint ventures		1

Fair Value of Financial Instruments (Schedule of Summarized Financial Information of Equity Method Investments) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Summarized Financial Information of Equity Method Investments
Current assets	$ 136.8	$ 89.5
Long-term assets	1,306.3	1,126.5
Total assets	1,443.1	1,216.0
Current liabilities	121.2	153.6
Long-term liabilities	976.5	986.0
Total liabilities	1,097.7	1,139.6
Revenue	114.5	0.0	$ 0.0
Net income (loss)	$ 64.5	$ (0.2)	$ (13.3)

Accounts Receivable, Net of Allowance (Schedule of Accounts Receivable, Net of Allowance) (Details) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Accounts Receivable, Net of Allowance
Contract billings	$ 683,900	$ 564,200
Retainage	323,100	268,600
Cost and earnings in excess of billings	599,200	331,600
Accounts receivable, gross	1,606,200	1,164,400
Less allowance for doubtful accounts	(8,200)	(8,400)	$ (7,700)
Accounts receivable, net	$ 1,598,015	$ 1,156,031

Accounts Receivable, Net of Allowance (Schedule of Activity, Allowance for Doubtful Accounts) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016
Allowance for Doubtful Accounts [Rollforward]
Allowance for doubtful accounts at beginning of year	$ 8.4	$ 7.7
Provision for doubtful accounts	2.6	2.9
Amounts charged against the allowance	(2.8)	(2.2)
Allowance for doubtful accounts at end of year	$ 8.2	$ 8.4

Accounts Receivable, Net of Allowance (Narrative) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Receivables, Non-Recourse Arrangement [Member] \| Interest Expense, Net [Member]
Schedule of Accounts Receivable, Net of Allowance [Line Items]
Non-recourse financing arrangement, discount charge	$ 6.0	$ 2.7	$ 1.6

Property and Equipment, Net (Schedule of Property and Equipment, Net) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016
Property and Equipment [Line Items]
Property and equipment	$ 1,455,600	$ 1,182,200
Less accumulated depreciation and amortization	(749,100)	(633,100)
Property and equipment, net	706,506	549,084
Land [Member]
Property and Equipment [Line Items]
Property and equipment	4,600	4,600
Building and Leasehold Improvements [Member]
Property and Equipment [Line Items]
Property and equipment	$ 26,700	24,200
Building and Leasehold Improvements [Member] \| Minimum [Member]
Property and Equipment [Line Items]
Estimated useful lives (in years)	3 years
Building and Leasehold Improvements [Member] \| Maximum [Member]
Property and Equipment [Line Items]
Estimated useful lives (in years)	40 years
Machinery and Equipment [Member]
Property and Equipment [Line Items]
Property and equipment	$ 1,261,900	997,800
Machinery and Equipment [Member] \| Minimum [Member]
Property and Equipment [Line Items]
Estimated useful lives (in years)	2 years
Machinery and Equipment [Member] \| Maximum [Member]
Property and Equipment [Line Items]
Estimated useful lives (in years)	20 years
Office Furniture and Equipment [Member]
Property and Equipment [Line Items]
Property and equipment	$ 149,900	146,100
Office Furniture and Equipment [Member] \| Minimum [Member]
Property and Equipment [Line Items]
Estimated useful lives (in years)	3 years
Office Furniture and Equipment [Member] \| Maximum [Member]
Property and Equipment [Line Items]
Estimated useful lives (in years)	7 years
Construction in Progress [Member]
Property and Equipment [Line Items]
Property and equipment	$ 12,500	$ 9,500

Property and Equipment, Net (Narrative) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Property and Equipment [Line Items]
Capitalized internal-use software, gross	$ 109,900	$ 107,800
Capitalized internal-use software, net	23,500	30,900
Depreciation and amortization	188,049	164,915	$ 169,662
Property and Equipment [Member]
Property and Equipment [Line Items]
Depreciation and amortization	$ 167,200	$ 143,600	$ 141,300

Debt (Schedule of Carrying Values of Debt) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016
Debt Instrument [Line Items]
Capital lease obligations	$ 181,200	$ 98,600
Total long-term debt obligations	1,381,600	1,035,800
Less unamortized deferred financing costs	(13,000)	(9,800)
Total debt, net of deferred financing costs	1,368,600	1,026,000
Current portion of long-term debt	87,866	64,600
Long-term debt	$ 1,280,706	961,379
Credit Facility [Member]
Debt Instrument [Line Items]
Line of credit facility, maturity date	Feb. 22, 2022
Credit Facility [Member] \| Revolving Loans [Member]
Debt Instrument [Line Items]
Long-term debt obligations	$ 377,700	279,900
Credit Facility [Member] \| Term Loan [Member]
Debt Instrument [Line Items]
Long-term debt obligations	396,900	237,500
Senior Notes [Member] \| 4.875% Senior Notes [Member]
Debt Instrument [Line Items]
Long-term debt obligations	$ 400,000	400,000
Debt instrument, interest rate (percentage)	4.875%
Debt instrument, maturity date	Mar. 15, 2023
Capital Lease Obligations [Member]
Debt Instrument [Line Items]
Debt instrument, weighted average interest rate (percentage)	3.50%
Capital lease obligations, expiration date, range, end	Sep. 01, 2022
Other Debt Obligations [Member]
Debt Instrument [Line Items]
Long-term debt obligations	$ 25,800	$ 19,800

Debt (Senior Secured Credit Facility) (Narrative) (Details) - Credit Facility [Member]			1 Months Ended		12 Months Ended
	Dec. 31, 2017 USD ($)	Dec. 31, 2016 USD ($)	Mar. 31, 2018 USD ($)	Dec. 31, 2017 USD ($)	Dec. 31, 2017 USD ($)	Feb. 22, 2017 USD ($)
Debt Instrument [Line Items]
Line of credit facility, maximum borrowing capacity		$ 1,200,000,000				$ 1,500,000,000
Line of credit facility, maturity date					Feb. 22, 2022
Line of credit facility, unused credit facility commitment fee (percentage)	0.25%	0.40%
Line of credit facility, letters of credit issued	$ 157,100,000	$ 314,300,000		$ 157,100,000	$ 157,100,000
Eurocurrency Rate [Member]
Debt Instrument [Line Items]
Line of credit facility, variable interest rate, margin over base rate, base rate equals option (iii) (percentage)	1.00%
Federal Funds Rate [Member]
Debt Instrument [Line Items]
Line of credit facility, variable interest rate, margin over base rate, base rate equals option (i) (percentage)	0.50%
Bank of America Prime Rate [Member]
Debt Instrument [Line Items]
Line of credit facility, variable interest rate, margin over base rate, base rate equals option (ii) (percentage)	0.00%
Maximum [Member]
Debt Instrument [Line Items]
Line of credit facility, revolving loans sublimit, Canadian dollars or Mexican pesos	$ 300,000,000			$ 300,000,000	$ 300,000,000
Line of credit facility, unused credit facility commitment fee (percentage)	0.40%	0.40%
Line of credit facility, required consolidated leverage ratio (in multiple)	3.50			3.50	3.50
Maximum [Member] \| Eurocurrency Rate [Member]
Debt Instrument [Line Items]
Line of credit facility, variable interest rate, margin over base rate (percentage)	2.00%	2.00%
Maximum [Member] \| Base Rate [Member]
Debt Instrument [Line Items]
Line of credit facility, variable interest rate, margin over base rate (percentage)	1.00%	1.00%
Minimum [Member]
Debt Instrument [Line Items]
Line of credit facility, unused credit facility commitment fee (percentage)	0.20%	0.20%
Line of credit facility, combined subsidiary guarantors percentage of consolidated EBITDA threshold (percentage)	70.00%			70.00%	70.00%
Line of credit facility, individual domestic subsidiary guarantors percentage of consolidated EBITDA threshold (percentage)	15.00%			15.00%	15.00%
Line of credit facility, required consolidated interest coverage ratio (in multiple)	3.0			3.0	3.0
Minimum [Member] \| Eurocurrency Rate [Member]
Debt Instrument [Line Items]
Line of credit facility, variable interest rate, margin over base rate (percentage)	1.25%	1.00%
Minimum [Member] \| Base Rate [Member]
Debt Instrument [Line Items]
Line of credit facility, variable interest rate, margin over base rate (percentage)	0.25%	0.00%
Plan [Member]
Debt Instrument [Line Items]
Line of credit facility, adjusted consolidated leverage ratio, permitted acquisitions amount, minimum threshold					$ 50,000,000
Plan [Member] \| Maximum [Member] \| Permitted Acquisition [Member]
Debt Instrument [Line Items]
Line of credit facility, required consolidated leverage ratio (in multiple)	3.75			3.75	3.75
Line of credit facility, adjusted consolidated leverage ratio, permitted acquisitions, maximum number of times right may be exercised	2			2	2
Revolving Loans [Member]
Debt Instrument [Line Items]
Line of credit facility, maximum borrowing capacity						1,100,000,000
Line of credit facility, amount of borrowings denominated in foreign currencies	$ 117,000,000	$ 119,000,000		$ 117,000,000	$ 117,000,000
Line of credit facility, remaining borrowing capacity	565,200,000	405,900,000		565,200,000	565,200,000
Line of credit facility, remaining borrowing capacity in Canadian dollars or Mexican pesos	$ 183,400,000	$ 80,900,000		$ 183,400,000	$ 183,400,000
Revolving Loans [Member] \| Weighted Average [Member]
Debt Instrument [Line Items]
Line of credit facility, interest rate (percentage)	3.69%	3.71%		3.69%	3.69%
Term Loan [Member]
Debt Instrument [Line Items]
Line of credit facility, maximum borrowing capacity						$ 400,000,000
Line of credit facility, term loan, frequency of payments					quarterly
Line of credit facility, term loan, amount of quarterly principal installment payments				$ 3,100,000
Line of credit facility, interest rate (percentage)	3.07%	2.77%		3.07%	3.07%
Term Loan [Member] \| Forecast [Member]
Debt Instrument [Line Items]
Line of credit facility, term loan, amount of quarterly principal installment payments			$ 5,000,000
Letters of Credit [Member]
Debt Instrument [Line Items]
Line of credit facility, maximum borrowing capacity	$ 650,000,000			$ 650,000,000	$ 650,000,000
Line of credit facility, capacity available for letters of credit	$ 492,900,000	$ 335,700,000		$ 492,900,000	$ 492,900,000
Letters of Credit [Member] \| Performance Standby [Member]
Debt Instrument [Line Items]
Line of credit facility, interest rate (percentage)	0.625%	1.00%		0.625%	0.625%
Letters of Credit [Member] \| Commercial and/or Financial Standby [Member]
Debt Instrument [Line Items]
Line of credit facility, interest rate (percentage)	1.50%	2.00%		1.50%	1.50%
Letters of Credit [Member] \| Maximum [Member]
Debt Instrument [Line Items]
Line of credit facility, capacity available for letters of credit sublimit, Canadian dollars or Mexican pesos	$ 200,000,000			$ 200,000,000	$ 200,000,000
Letters of Credit [Member] \| Maximum [Member] \| Performance Standby [Member]
Debt Instrument [Line Items]
Line of credit facility, interest rate (percentage)	1.00%	1.00%		1.00%	1.00%
Letters of Credit [Member] \| Maximum [Member] \| Commercial and/or Financial Standby [Member]
Debt Instrument [Line Items]
Line of credit facility, interest rate (percentage)	2.00%	2.00%		2.00%	2.00%
Letters of Credit [Member] \| Minimum [Member] \| Performance Standby [Member]
Debt Instrument [Line Items]
Line of credit facility, interest rate (percentage)	0.50%	0.50%		0.50%	0.50%
Letters of Credit [Member] \| Minimum [Member] \| Commercial and/or Financial Standby [Member]
Debt Instrument [Line Items]
Line of credit facility, interest rate (percentage)	1.25%	1.00%		1.25%	1.25%
Swing Line Loans [Member] \| Maximum [Member]
Debt Instrument [Line Items]
Line of credit facility, swing line loans sublimit	$ 75,000,000			$ 75,000,000	$ 75,000,000
Accordion Feature [Member] \| Plan [Member]
Debt Instrument [Line Items]
Line of credit facility, maximum borrowing capacity	$ 250,000,000			$ 250,000,000	$ 250,000,000

Debt (Senior Secured Credit Facility) (Terms, Guarantees and Covenants) (Narrative) (Details) - Credit Facility [Member]	12 Months Ended
	Dec. 31, 2017
Debt Instrument [Line Items]
Line of credit facility, description of variable rate	Outstanding revolving loans and the term loan under the Credit Facility bear interest, at the Company’s option, at a rate equal to either (a) a Eurocurrency Rate, as defined in the 2017 Credit Facility, plus a margin of 1.25% to 2.00% (under the 2016 Credit Facility, the margin was from 1.00% to 2.00%), or (b) a Base Rate, as defined in the 2017 Credit Facility, plus a margin of 0.25% to 1.00% (under the 2016 Credit Facility, the margin was from 0.00% to 1.00%). The Base Rate equals the highest of (i) the Federal Funds Rate, as defined in the Credit Facility, plus 0.50%, (ii) Bank of America’s prime rate, and (iii) the Eurocurrency Rate plus 1.00%.
Line of credit facility, commitment fee description	The Company must also pay a commitment fee to the lenders of 0.20% to 0.40% on any unused availability under the Credit Facility.
Line of credit facility, collateral	The Credit Facility is guaranteed by certain subsidiaries of the Company (the “Guarantor Subsidiaries”) and the obligations under the Credit Facility are secured by substantially all of the Company’s and the Guarantor Subsidiaries’ respective assets, subject to certain exceptions. Under the Credit Facility, if the “Loan Party EBITDA,” as defined in the Credit Facility, as of the last four consecutive fiscal quarters does not represent at least 70% of the “Adjusted Consolidated EBITDA,” as defined in the Credit Facility, for such period, then the Company must designate additional subsidiaries as Guarantor Subsidiaries, and cause them to join the applicable guaranty and security agreements to the Credit Facility. Additionally, any domestic subsidiary with consolidated EBITDA of at least 15% of the Adjusted Consolidated EBITDA must become a Guarantor Subsidiary and join the applicable guaranty and security agreements.
Line of credit facility, covenant terms	The Credit Facility requires that the Company maintain a Maximum Consolidated Leverage Ratio, as defined in the Credit Facility, of 3.50 (subject to the Acquisition Adjustment described below). The Credit Facility also requires that the Company maintain a Minimum Consolidated Interest Coverage Ratio, as defined in the Credit Facility, of 3.00. The Credit Facility provides that, for purposes of calculating the Consolidated Leverage Ratio, certain cash charges may be added back to the calculation of Consolidated EBITDA, as defined in the Credit Facility, and funded indebtedness excludes undrawn standby performance letters of credit and is further reduced by unrestricted cash over certain thresholds. Additionally, notwithstanding the terms discussed above, subject to certain conditions, if a permitted acquisition or series of permitted acquisitions having consideration exceeding $50 million occurs during a fiscal quarter, the Consolidated Leverage Ratio may be temporarily increased to up to 3.75 during such fiscal quarter and the subsequent two fiscal quarters. Such right may be exercised no more than two times during the term of the Credit Facility. Subject to customary exceptions, the Credit Facility limits the borrowers’ and the Guarantor Subsidiaries’ ability to engage in certain activities, including acquisitions, mergers and consolidations, debt incurrence, investments, capital expenditures, asset sales, debt prepayments, lien incurrence and the making of distributions or repurchases of capital stock. However, distributions payable solely in capital stock are permitted. The Credit Facility provides for customary events of default and carries cross-default provisions with the Company’s other significant debt instruments, including the Company’s indemnity agreement with its surety provider, as well as customary remedies, including the acceleration of repayment of outstanding amounts and other remedies with respect to the collateral securing the Credit Facility obligations.
Letters of Credit [Member]
Debt Instrument [Line Items]
Line of credit facility, interest rate description, letters of credit	Financial standby letters of credit and commercial letters of credit issued under the 2017 Credit Facility are subject to a letter of credit fee of 1.25% to 2.00% (under the 2016 Credit Facility, the letter of credit fee was from 1.00% to 2.00%), and performance standby letters of credit are subject to a letter of credit fee of 0.50% to 1.00% under the Credit Facility.

Debt (Other Credit Facilities) (Narrative) (Details) - Other Credit Facilities [Member] $ in Millions, $ in Millions	12 Months Ended
	Dec. 31, 2017 USD ($)	Dec. 31, 2017 CAD ($)	Dec. 31, 2016 USD ($)	Dec. 31, 2016 CAD ($)
Debt Instrument [Line Items]
Line of credit facility, maximum borrowing capacity (in dollars)		$ 20.0		$ 40.0
Debt instrument, rationale for classification as long-term debt	Outstanding borrowings that are not renewed are repaid with borrowings under the Credit Facility. Accordingly, the carrying amounts of the Company’s borrowings under its other credit facilities, which are included within other debt obligations in the table above, are classified within long-term debt in the Company’s consolidated balance sheets.
Weighted Average [Member]
Debt Instrument [Line Items]
Line of credit facility, interest rate (percentage)	4.00%	4.00%	3.60%	3.60%
Canadian Dollars [Member]
Debt Instrument [Line Items]
Line of credit facility, maximum borrowing capacity (in dollars)	$ 15.9		$ 29.8
Long-term debt obligations (in dollars)	$ 10.4		$ 13.4

Debt (4.875% Senior Notes) (Narrative) (Details) - Senior Notes [Member] - 4.875% Senior Notes [Member]	12 Months Ended
	Dec. 31, 2017 USD ($)
Debt Instrument [Line Items]
Debt instrument, principal amount (in dollars)	$ 400,000,000
Debt instrument, interest rate (percentage)	4.875%
Debt instrument, maturity date	Mar. 15, 2023
Debt instrument, interest payment terms	Interest on the 4.875% Senior Notes is payable on March 15 and September 15 of each year.
Debt instrument, guarantees	are fully and unconditionally guaranteed on an unsecured, unsubordinated, joint and several basis by certain of the Company’s existing and future 100%-owned direct and indirect domestic subsidiaries that are each guarantors of the Credit Facility or other outstanding indebtedness.
Debt instrument, restrictive covenants	The 4.875% Senior Notes Indenture, among other things, generally limits the ability of the Company and certain of its subsidiaries, subject to certain exceptions, to (i) incur additional debt and issue preferred stock, (ii) create liens, (iii) pay dividends, acquire shares of capital stock, make payments on subordinated debt or make investments, (iv) place limitations on distributions from certain subsidiaries, (v) issue guarantees, (vi) issue or sell the capital stock of certain subsidiaries, (vii) sell assets, (viii) enter into transactions with affiliates and (ix) effect mergers. The 4.875% Senior Notes Indenture provides for customary events of default, as well as customary remedies upon an event of default, as defined in the 4.875% Senior Notes Indenture, including acceleration of repayment of outstanding amounts.
Debt Instrument, Redemption, on or after March 15, 2018 [Member]
Debt Instrument [Line Items]
Debt instrument, redemption description	The Company has the option to redeem all or a portion of the 4.875% Senior Notes at any time on or after March 15, 2018 at the redemption prices set forth in the indenture that governs the 4.875% Senior Notes (the “4.875% Senior Notes Indenture”) plus accrued and unpaid interest, if any, to the redemption date.
Debt instrument, redemption period, start date	Mar. 15, 2018
Debt Instrument, Redemption, on or after March 15, 2018 [Member] \| Plan [Member] \| Maximum [Member]
Debt Instrument [Line Items]
Debt instrument, percentage of principal that may be redeemed	100.00%
Redemption Period prior to March 15, 2018 [Member]
Debt Instrument [Line Items]
Debt instrument, call feature description	At any time prior to March 15, 2018, the Company may redeem all or a part of the 4.875% Senior Notes at a redemption price equal to 100% of the principal amount of 4.875% Senior Notes redeemed plus an applicable premium, as defined in the 4.875% Senior Notes Indenture, together with accrued and unpaid interest, if any, to the redemption date.
Debt instrument, redemption period, end date	Mar. 15, 2018
Redemption Period prior to March 15, 2018 [Member] \| Plan [Member] \| Maximum [Member]
Debt Instrument [Line Items]
Debt instrument, percentage of principal that may be redeemed	100.00%
Redemption Period prior to March 15, 2018 [Member] \| Plan [Member] \| Minimum [Member]
Debt Instrument [Line Items]
Debt instrument, redemption price, percentage of principal amount	100.00%

Debt (Schedule of Contractual Maturities of Debt and Capital Lease Obligations) (Details) - USD ($) $ in Millions	Dec. 31, 2017	Dec. 31, 2016
Contractual Maturities of Debt and Capital Lease Obligations
Contractual maturities of debt and capital lease obligations, 2018	$ 88.3
Contractual maturities of debt and capital lease obligations, 2019	65.5
Contractual maturities of debt and capital lease obligations, 2020	57.0
Contractual maturities of debt and capital lease obligations, 2021	46.4
Contractual maturities of debt and capital lease obligations, 2022	724.4
Contractual maturities of debt and capital lease obligations, thereafter	400.0
Total long-term debt obligations	$ 1,381.6	$ 1,035.8

Debt (Other) (Narrative) (Details) - USD ($) $ in Millions	Dec. 31, 2017	Dec. 31, 2016
Other Accrued Expenses [Member]
Debt Instrument [Line Items]
Debt instruments, accrued interest payable	$ 7.4	$ 8.5

Lease Obligations (Capital Leases) (Narrative) (Details) - Property and Equipment [Member] - USD ($) $ in Millions	Dec. 31, 2017	Dec. 31, 2016
Capital Leases [Line Items]
Assets held under capital lease, gross	$ 418.0	$ 294.9
Assets held under capital lease, net	$ 277.3	$ 177.5

Lease Obligations (Operating Leases) (Narrative) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Lease Terms in Excess of One Year [Member]
Operating Leases [Line Items]
Operating leases, rent and related expense (in dollars)	$ 104.2	$ 100.5	$ 81.8
Lease Terms in Excess of One Year [Member] \| Minimum [Member]
Operating Leases [Line Items]
Operating leases, term of contract (in years)	1 year	1 year	1 year
Lease Terms of One Year or Less [Member]
Operating Leases [Line Items]
Operating leases, rent and related expense (in dollars)	$ 461.0	$ 298.0	$ 196.2
Lease Terms of One Year or Less [Member] \| Maximum [Member]
Operating Leases [Line Items]
Operating leases, term of contract (in years)	1 year	1 year	1 year

Lease Obligations (Schedule of Future Lease Commitments) (Details) - USD ($) $ in Millions	Dec. 31, 2017	Dec. 31, 2016
Capital Leases
Future minimum lease commitments, 2018	$ 69.5
Future minimum lease commitments, 2019	49.4
Future minimum lease commitments, 2020	39.4
Future minimum lease commitments, 2021	29.0
Future minimum lease commitments, 2022	9.1
Future minimum lease commitments, thereafter	0.0
Total minimum lease payments	196.4
Less amounts representing interest	(15.2)
Total capital lease obligations, net of interest	181.2	$ 98.6
Less current portion	(63.5)
Long-term portion of capital lease obligations, net of interest	117.7
Operating Leases
Future minimum lease commitments, 2018	90.7
Future minimum lease commitments, 2019	57.3
Future minimum lease commitments, 2020	33.9
Future minimum lease commitments, 2021	19.2
Future minimum lease commitments, 2022	12.3
Future minimum lease commitments, thereafter	30.3
Total minimum lease payments	$ 243.7

Stock-Based Compensation and Other Employee Benefit Plans (Narrative) (Details)	12 Months Ended
	Dec. 31, 2017 shares
Common Stock [Member]
Stock-Based Compensation and Other Employee Benefit Plans [Line Items]
Stock-based compensation, number of shares available for grant or issuance	4,811,000
Employee Stock Purchase Plans [Member]
Stock-Based Compensation and Other Employee Benefit Plans [Line Items]
Stock-based compensation plan, description	The Company has certain employee stock purchase plans under which shares of the Company’s common stock are available for purchase by eligible employees. These plans allow qualified employees to purchase MasTec, Inc. common stock at 85% of its fair market value at the lower of (i) the date of commencement of the offering period or (ii) the last day of the exercise period, as defined in the plan documents.
2013 Incentive Plan [Member] \| Restricted Shares [Member]
Stock-Based Compensation and Other Employee Benefit Plans [Line Items]
Stock-based compensation plan, description	The 2013 Incentive Plan permits a total of approximately 7,391,000 shares of the Company’s common stock to be issued.
2013 Incentive Plan [Member] \| Restricted Shares [Member] \| Common Stock [Member]
Stock-Based Compensation and Other Employee Benefit Plans [Line Items]
Stock-based compensation plan, number of shares authorized	7,391,000
ESPPs [Member] \| Employee Stock Purchase Plans [Member]
Stock-Based Compensation and Other Employee Benefit Plans [Line Items]
Stock-based compensation plan, description	Under the Company’s ESPPs, shares of the Company’s common stock are available for purchase by eligible employees, which collectively permit the issuance of up to 3,000,000 new shares of MasTec, Inc. common stock.
ESPPs [Member] \| Employee Stock Purchase Plans [Member] \| Common Stock [Member]
Stock-Based Compensation and Other Employee Benefit Plans [Line Items]
Stock-based compensation plan, number of shares authorized	3,000,000

Stock-Based Compensation and Other Employee Benefit Plans (Restricted Shares) (Narrative) (Details) - Restricted Shares [Member] - USD ($) $ in Millions		12 Months Ended
	Dec. 31, 2017	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Stock-Based Compensation and Other Employee Benefit Plans [Line Items]
Stock-based compensation awards, unearned compensation	$ 20.4	$ 20.4
Stock-based compensation awards, unearned compensation, weighted average expected recognition period (in years)	1 year 6 months
Stock-based compensation, vested awards, intrinsic value		$ 39.7	$ 3.5	$ 8.1

Stock-Based Compensation and Other Employee Benefit Plans (Schedule of Activity, Restricted Shares) (Details) - Common Stock [Member] - $ / shares

12 Months Ended

Dec. 31, 2017

Dec. 31, 2016

Restricted Shares [Member]

Restricted Shares

Non-vested restricted shares, beginning balance (in shares)

^[1]

1,970,586

1,630,232

Granted (in shares)

429,061

637,332

Vested (in shares)

(899,815)

(188,386)

Canceled/forfeited (in shares)

(51,241)

(108,592)

Non-vested restricted shares, ending balance (in shares)

^[1]

1,448,591

1,970,586

Per Share Weighted Average Grant Date Fair Value

Non-vested restricted shares, per share weighted average grant date fair value, beginning balance (in dollars per share)

$ 21.61

$ 22.94

Granted (in dollars per share)

40.46

17.69

Vested (in dollars per share)

28.08

20.42

Canceled/forfeited (in dollars per share)

18.22

20.71

Non-vested restricted shares, per share weighted average grant date fair value, ending balance (in dollars per share)

$ 23.29

$ 21.61

Restricted Stock Units [Member]

Restricted Shares

Non-vested restricted shares, beginning balance (in shares)

43,300

32,250

Non-vested restricted shares, ending balance (in shares)

27,550

43,300

[1]	Includes 27,550, 43,300 and 32,250 restricted stock units as of December 31, 2017, 2016 and 2015, respectively.

Stock-Based Compensation and Other Employee Benefit Plans (Schedule of Activity, Employee Stock Purchase Plans) (Details) - USD ($) $ / shares in Units, $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Common Stock [Member]
Stock-Based Compensation and Other Employee Benefit Plans [Line Items]
Common shares issued (in shares)	92,145	144,183	134,389
Employee Stock Purchase Plans [Member]
Stock-Based Compensation and Other Employee Benefit Plans [Line Items]
Cash proceeds (in dollars)	$ 3.3	$ 2.7	$ 2.0
Employee Stock Purchase Plans [Member] \| Common Stock [Member]
Stock-Based Compensation and Other Employee Benefit Plans [Line Items]
Weighted average price per share (in dollars per share)	$ 35.92	$ 18.55	$ 14.67
Weighted average per share grant date fair value (in dollars per share)	$ 9.24	$ 5.00	$ 4.22

Stock-Based Compensation and Other Employee Benefit Plans (Stock Options) (Narrative) (Details) - USD ($) $ / shares in Units, $ in Millions	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015
Stock-Based Compensation and Other Employee Benefit Plans [Line Items]
Stock options exercised, intrinsic value	$ 1.8	$ 0.8
Stock options exercised, proceeds, net of shares withheld	$ 2.1	$ 0.5
Common Stock [Member]
Stock-Based Compensation and Other Employee Benefit Plans [Line Items]
Stock-based compensation, options outstanding (in shares)	0	202,700
Stock-based compensation, options exercised (in shares)	202,700	81,971
Common Stock [Member] \| Stock Options [Member]
Stock-Based Compensation and Other Employee Benefit Plans [Line Items]
Stock options exercised, per share weighted average exercise price	$ 13.06

Stock-Based Compensation and Other Employee Benefit Plans (Schedule of Non-Cash Stock-Based Compensation Expense) (Details) - USD ($)
$ in Thousands

3 Months Ended

12 Months Ended

Dec. 31, 2017

Dec. 31, 2016

Dec. 31, 2015

Stock-Based Compensation and Other Employee Benefit Plans [Line Items]

Non-cash stock-based compensation expense

$ 15,656

$ 15,072

$ 12,395

Income Tax Effects:

Income tax effect of non-cash stock-based compensation

11,200

5,600

4,200

Excess tax benefit from non-cash stock-based compensation

^[1]

5,700

100

Tax benefit, net

(22,942)

(91,784)

(11,957)

Share-Based Compensation [Member]

Income Tax Effects:

Tax benefit, net

$ 5,600

5,400

General and Administrative Expenses [Member]

Stock-Based Compensation and Other Employee Benefit Plans [Line Items]

Non-cash stock-based compensation expense

$ 15,700

$ 15,100

$ 12,400

[1]

Excess tax benefits represent cash flows from tax deductions in excess of the tax effect of compensation expense associated with share-based payment arrangements. For the year ended December 31, 2017, the Company recognized a tax benefit of $5.4 million, net of tax deficiencies, related to the vesting of share-based payment awards.

Stock-Based Compensation and Other Employee Benefit Plans (401(k) Plan) (Narrative) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
401(k) Plan Disclosure [Line Items]
Stock-based compensation plan, description	MasTec has a 401(k) plan covering all eligible employees. Subject to certain dollar limits, eligible employees may contribute up to 75% of their pre-tax annual compensation to the 401(k) plan. The Company’s matching contribution is equal to 100% of the first 3% of the employee’s salary and 50% of the next 2% of the employee’s salary, up to a maximum 4% employer match. Discretionary matching contributions, which are payable 50% in shares of MasTec common stock and 50% in cash, are paid quarterly.
401(k) plan, maximum pre-tax annual contribution per employee, percentage of annual compensation	75.00%
401(k) plan, employer matching contribution, percentage of matching contribution for first 3% of employee's salary	100.00%
401(k) plan, employer 100% matching contribution, percentage of employee's salary	3.00%
401(k) plan, employer matching contribution, percentage of matching contribution for 3% to 5% of employee's salary	50.00%
401(k) plan, employer 50% matching contribution, additional percentage of employee's salary	2.00%
401(k) plan, discretionary employer matching contribution, percentage of matching contribution payable in shares	50.00%
401(k) plan, discretionary employer matching contribution, percentage of matching contribution payable in cash	50.00%
401(k) plan, employer matching contribution (in dollars)	$ 11.9	$ 11.1	$ 10.2
Maximum [Member]
401(k) Plan Disclosure [Line Items]
401(k) plan, employer matching contribution, percentage of employee's salary	4.00%

Stock-Based Compensation and Other Employee Benefit Plans (Deferred Compensation Plans) (Narrative) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016
Deferred Compensation Arrangements [Abstract]
Deferred compensation plans, description	MasTec offers a deferred compensation plan to its highly compensated employees. These employees are allowed to contribute a percentage of their pre-tax annual compensation to the deferred compensation plan. The Company also offers a deferred compensation plan to its Board of Directors, under which directors may elect to defer the receipt of compensation for their services.
Deferred compensation plans, assets	$ 9.4	$ 7.7
Deferred compensation plans, liabilities	$ 9.7	$ 7.6

Other Retirement Plans (Narrative) (Details)	12 Months Ended
Other Retirement Plans (Narrative) (Details)	Dec. 31, 2017
Multiemployer Plans [Line Items]
Multiemployer plans, general nature	certain of MasTec’s subsidiaries are party to various collective bargaining agreements with unions representing certain of their employees, which require the Company to pay specified wages, provide certain benefits to their union employees and contribute certain amounts to MEPPs.
Multiemployer Plans, Pension [Member]
Multiemployer Plans [Line Items]
Multiemployer plans, underfunded status, description	A multiemployer plan that is so underfunded as to be in “endangered,” “seriously endangered,” “critical,” or “critical and declining” status (as determined under the PPA) is required to adopt a funding improvement plan (“FIP”) or a rehabilitation plan (“RP”), which, among other actions, could include decreased benefits and increased employer contributions, which could take the form of a surcharge on benefit contributions. These actions are intended to improve their funding status over a period of years. If a pension fund is in critical status, a participating employer must pay an automatic surcharge in addition to contributions otherwise required under the collective bargaining agreement (“CBA”). With some exceptions, the surcharge is equal to 5% of required contributions for the initial critical year and 10% for each succeeding plan year in which the plan remains in critical status. The surcharge ceases on the effective date of a CBA (or other agreement) that includes contribution and benefit terms consistent with the rehabilitation plan. Certain plans in which the Company participates are in “endangered,” “seriously endangered,” “critical,” or “critical and declining” status. The amount of additional funds, if any, that the Company may be obligated to contribute to these plans in the future cannot be estimated due to the uncertainty of the future levels of work that could be required of the union employees covered by these plans, as well as the required future contribution rates and possible surcharges applicable to these plans.

Other Retirement Plans (Schedule of Multiemployer Pension Plans) (Details) - USD ($)
$ in Millions

12 Months Ended

Dec. 31, 2017

Dec. 31, 2016

Dec. 31, 2015

Multiemployer Plans, Pension [Member]

$ 102.4

$ 70.0

$ 32.8

Multiemployer Plans, Pension [Member] | Pipeline Industry Pension Fund [Member]

$ 92.1

59.9

23.8

Multiemployer plans, employer identification number

736146433

001

Multiemployer plans, collective bargaining arrangement, expiration date

$ 28.8

$ 15.9

2.5

May 31, 2020

Multiemployer plans, pension protection act zone status

Green

Multiemployer plans, pension protection act zone status, date

^[1]

Dec. 31, 2016

Dec. 31, 2015

Multiemployer plans, Company contributions greater than 5% of total plan contributions

true

Multiemployer plans, funding improvement plan and rehabilitation plan status

Multiemployer Plans, Pension [Member] | Central Pension Fund of IUOE and Participating Employers [Member]

Multiemployer plans, employer identification number

366052390

001

Multiemployer plans, collective bargaining arrangement, expiration date

$ 21.6

$ 19.3

5.7

Jun. 01, 2020

Multiemployer plans, pension protection act zone status

Green

Multiemployer plans, pension protection act zone status, date

Jan. 31, 2017

Jan. 31, 2016

Multiemployer plans, funding improvement plan and rehabilitation plan status

Multiemployer Plans, Pension [Member] | Teamsters National Pipe Line Pension Plan [Member]

Multiemployer plans, employer identification number

461102851

001

Multiemployer plans, collective bargaining arrangement, expiration date

$ 7.6

$ 3.6

1.4

May 31, 2020

Multiemployer plans, pension protection act zone status

Green

Multiemployer plans, pension protection act zone status, date

^[1]

Dec. 31, 2016

Dec. 31, 2015

Multiemployer plans, Company contributions greater than 5% of total plan contributions

true

Multiemployer plans, funding improvement plan and rehabilitation plan status

Multiemployer Plans, Pension [Member] | Ohio Operating Engineers Pension Plan [Member]

Multiemployer plans, employer identification number

316129968

001

Multiemployer plans, collective bargaining arrangement, expiration date

$ 4.9

$ 0.0

0.0

Jun. 01, 2020

Multiemployer plans, pension protection act zone status

Green

Multiemployer plans, pension protection act zone status, date

Jul. 31, 2016

Jul. 31, 2015

Multiemployer plans, funding improvement plan and rehabilitation plan status

Multiemployer Plans, Pension [Member] | Laborers' National Pension Fund [Member]

Multiemployer plans, employer identification number

751280827

001

Multiemployer plans, collective bargaining arrangement, expiration date

$ 3.5

$ 3.0

0.8

May 31, 2020

Multiemployer plans, pension protection act zone status

Green

Multiemployer plans, pension protection act zone status, date

Dec. 31, 2016

Dec. 31, 2015

Multiemployer plans, funding improvement plan and rehabilitation plan status

Multiemployer Plans, Pension [Member] | West Virginia Laborers' Pension Trust Fund [Member]

Multiemployer plans, employer identification number

556026775

001

Multiemployer plans, collective bargaining arrangement, expiration date

$ 3.0

$ 0.5

1.4

May 31, 2020

Multiemployer plans, pension protection act zone status

Green

Multiemployer plans, pension protection act zone status, date

Mar. 31, 2017

Mar. 31, 2016

^[1]

Multiemployer plans, Company contributions greater than 5% of total plan contributions

true

Multiemployer plans, funding improvement plan and rehabilitation plan status

Multiemployer Plans, Pension [Member] | Laborers' District Council & Contractors Pension Fund of Ohio [Member]

Multiemployer plans, employer identification number

316129964

001

Multiemployer plans, collective bargaining arrangement, expiration date

$ 2.5

$ 0.5

0.2

May 31, 2020

Multiemployer plans, pension protection act zone status

Green

Multiemployer plans, pension protection act zone status, date

Dec. 31, 2016

Dec. 31, 2015

Multiemployer plans, funding improvement plan and rehabilitation plan status

Multiemployer Plans, Pension [Member] | International Union of Operating Engineers Local 132 Pension Fund [Member]

Multiemployer plans, employer identification number

556015364

001

Multiemployer plans, collective bargaining arrangement, expiration date

$ 2.3

$ 0.2

1.9

Jun. 01, 2020

Multiemployer plans, pension protection act zone status

Green

Multiemployer plans, pension protection act zone status, date

Mar. 31, 2017

Mar. 31, 2016

^[1]

Multiemployer plans, Company contributions greater than 5% of total plan contributions

true

Multiemployer plans, funding improvement plan and rehabilitation plan status

Multiemployer Plans, Pension [Member] | Operating Engineers Local 324 Pension Fund [Member]

Multiemployer plans, employer identification number

381900637

001

Multiemployer plans, collective bargaining arrangement, expiration date

$ 2.1

$ 0.0

0.0

Jun. 01, 2020

Multiemployer plans, pension protection act zone status

Red

Multiemployer plans, pension protection act zone status, date

Apr. 30, 2017

Apr. 30, 2016

Multiemployer plans, funding improvement plan and rehabilitation plan status

Implemented

Multiemployer Plans, Pension [Member] | Michigan Laborers' Pension Plan [Member]

Multiemployer plans, employer identification number

386233976

001

Multiemployer plans, collective bargaining arrangement, expiration date

$ 2.0

$ 1.1

0.8

May 31, 2020

Multiemployer plans, pension protection act zone status

Yellow

Multiemployer plans, pension protection act zone status, date

Aug. 31, 2017

Aug. 31, 2016

^[2]

Multiemployer plans, extended amortization provisions

true

Multiemployer plans, funding improvement plan and rehabilitation plan status

Implemented

Multiemployer Plans, Pension [Member] | National Electrical Benefit Fund [Member]

Multiemployer plans, employer identification number

530181657

001

Multiemployer plans, pension protection act zone status

$ 1.8

$ 1.7

1.4

Green

Multiemployer plans, pension protection act zone status, date

Dec. 31, 2016

Dec. 31, 2015

Multiemployer plans, funding improvement plan and rehabilitation plan status

Multiemployer Plans, Pension [Member] | National Electrical Benefit Fund [Member] | Maximum [Member]

Multiemployer plans, collective bargaining arrangement, expiration date

Sep. 06, 2020

Multiemployer Plans, Pension [Member] | Laborers' Local Union No. 158 Pension Plan [Member]

Multiemployer plans, employer identification number

236580323

001

Multiemployer plans, collective bargaining arrangement, expiration date

$ 1.8

$ 0.4

0.7

May 31, 2020

Multiemployer plans, pension protection act zone status

Green

Multiemployer plans, pension protection act zone status, date

Dec. 31, 2016

Dec. 31, 2015

^[1]

Multiemployer plans, Company contributions greater than 5% of total plan contributions

true

Multiemployer plans, funding improvement plan and rehabilitation plan status

Multiemployer Plans, Pension [Member] | IBEW Local 1249 Pension Plan [Member]

Multiemployer plans, employer identification number

156035161

001

Multiemployer plans, collective bargaining arrangement, expiration date

$ 1.5

$ 1.1

1.0

May 02, 2021

Multiemployer plans, pension protection act zone status

Yellow

Multiemployer plans, pension protection act zone status, date

Dec. 31, 2016

Dec. 31, 2015

Multiemployer plans, funding improvement plan and rehabilitation plan status

Implemented

Multiemployer Plans, Pension [Member] | Central Laborers' Pension Fund [Member]

Multiemployer plans, employer identification number

376052379

001

Multiemployer plans, collective bargaining arrangement, expiration date

$ 0.5

$ 2.6

0.0

May 31, 2020

Multiemployer plans, pension protection act zone status

Yellow

Red

Multiemployer plans, pension protection act zone status, date

^[2]

Dec. 31, 2016

Dec. 31, 2015

Multiemployer plans, extended amortization provisions

true

Multiemployer plans, funding improvement plan and rehabilitation plan status

Implemented

Multiemployer Plans, Pension [Member] | Other Funds [Member]

Multiemployer Plans, Pension [Member] | Other Funds [Member] | Canada [Member]

^[3]

$ 8.2

$ 10.0

6.0

$ 0.7

$ 0.9

$ 1.4

[1]	The Company’s contributions to this plan represent greater than 5% of the plan’s total contributions.
[2]	This plan has utilized extended amortization provisions, which provide plans with extensions of time to amortize pension funding shortfalls.
[3]	The 2017, 2016 and 2015 contributions include approximately $0.7 million, $0.9 million and $1.4 million, respectively, for Canadian multiemployer pension plans. Canadian multiemployer pension plans are not subject to the provisions of ERISA or the funding rules under the PPA that apply to U.S. registered multiemployer pension plans. Contributions to Canadian multiemployer pension plans are based on fixed amounts per hour per employee for employees covered under these plans.

Other Retirement Plans (Schedule of Covered Employees and Contributions, Multiemployer Plans) (Details) $ in Millions	12 Months Ended
	Dec. 31, 2017 USD ($) employee	Dec. 31, 2016 USD ($) employee	Dec. 31, 2015 USD ($) employee
Covered Employees and Contributions, Multiemployer Plans [Line Items]
Multiemployer plans, contributions (in dollars)	$ 102.4	$ 70.0	$ 32.8
Multiemployer Plans, Pension [Member]
Covered Employees and Contributions, Multiemployer Plans [Line Items]
Multiemployer plans, contributions (in dollars)	92.1	59.9	23.8
Multiemployer Plans, Other Multiemployer [Member]
Covered Employees and Contributions, Multiemployer Plans [Line Items]
Multiemployer plans, contributions (in dollars)	$ 10.3	$ 10.1	$ 9.0
Workforce Subject to Collective Bargaining Arrangements [Member] \| Unionized Employees [Member] \| Low [Member]
Covered Employees and Contributions, Multiemployer Plans [Line Items]
Multiemployer plans, covered employees (in number of employees) \| employee	550	550	590
Workforce Subject to Collective Bargaining Arrangements [Member] \| Unionized Employees [Member] \| High [Member]
Covered Employees and Contributions, Multiemployer Plans [Line Items]
Multiemployer plans, covered employees (in number of employees) \| employee	7,057	4,910	2,463

Equity (Narrative) (Details) - USD ($)	12 Months Ended
Equity (Narrative) (Details) - USD ($)	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015	Feb. 25, 2016
Equity, Treasury Stock [Line Items]
Treasury stock acquired, value	$ 1,551,000		$ 100,000,000
Treasury Stock, Common [Member]
Equity, Treasury Stock [Line Items]
Treasury stock acquired (in shares)	38,807		5,217,693
Treasury stock acquired, value	$ 1,551,000		$ 100,000,000
2016 Share Repurchase Program [Member]
Equity, Treasury Stock [Line Items]
Share repurchase program, amount authorized, value				$ 100,000,000
Treasury stock acquired, value	$ 1,600,000
2016 Share Repurchase Program [Member] \| Treasury Stock, Common [Member]
Equity, Treasury Stock [Line Items]
Treasury stock acquired (in shares)	38,800	0
2014 Share Repurchase Program [Member]
Equity, Treasury Stock [Line Items]
Treasury stock acquired, value			$ 100,000,000
2014 Share Repurchase Program [Member] \| Treasury Stock, Common [Member]
Equity, Treasury Stock [Line Items]
Treasury stock acquired (in shares)			5,200,000

Equity (Schedule of Changes in Accumulated Other Comprehensive Loss) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Accumulated Other Comprehensive Loss [Line Items]
Accumulated other comprehensive loss, beginning balance	$ (65,814)	$ (72,351)	$ (34,004)
Unrealized gains (losses), net of tax	2,102	6,537	(38,347)
Accumulated other comprehensive loss, ending balance	(63,712)	(65,814)	(72,351)
Foreign Currency [Member]
Accumulated Other Comprehensive Loss [Line Items]
Accumulated other comprehensive loss, beginning balance	(64,478)	(67,063)	(28,716)
Unrealized gains (losses), net of tax	1,627	2,585	(38,347)
Accumulated other comprehensive loss, ending balance	(62,851)	(64,478)	(67,063)
Other [Member]
Accumulated Other Comprehensive Loss [Line Items]
Accumulated other comprehensive loss, beginning balance	(1,336)	(5,288)	(5,288)
Unrealized gains (losses), net of tax	475	3,952	0
Accumulated other comprehensive loss, ending balance	$ (861)	$ (1,336)	$ (5,288)

Income Taxes (Schedule of Components of Income (Loss) before Income Taxes) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Income Tax Disclosure [Abstract]
Domestic	$ 334,900	$ 202,400	$ (26,500)
Foreign	36,900	23,400	(41,200)
Income (loss) before income taxes	$ 371,826	$ 225,819	$ (67,746)

Income Taxes (Schedule of Provision for Income Taxes) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Current:
Federal	$ (6,000)	$ 85,800	$ (4,500)
Foreign	11,500	3,000	9,400
State and local	(800)	6,700	3,300
Total current income tax expense	4,700	95,500	8,200
Deferred:
Federal	18,200	6,100	25,700
Foreign	(7,500)	(6,800)	(19,900)
State and local	7,600	(3,000)	(2,000)
Total deferred income tax expense	18,277	(3,935)	3,925
Provision for income taxes	22,942	91,784	11,957
Continuing Operations [Member]
Deferred:
Total deferred income tax expense	$ 18,300	$ (3,700)	$ 3,800

Income Taxes (Schedule of Deferred Tax Assets and Liabilities) (Details) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Deferred tax assets:
Accrued insurance	$ 24,600	$ 31,100
Operating loss carryforwards and tax credits	54,900	34,900
Unrealized gains and losses	11,400	26,300
Compensation and benefits	7,500	24,100
Bad debt	1,200	4,700
Other	7,900	12,400
Valuation allowance	(40,500)	(21,400)
Total deferred tax assets	67,000	112,100
Deferred tax liabilities:
Property and equipment	104,100	126,600
Goodwill	56,700	72,800
Other intangible assets	28,700	32,900
Investments in unconsolidated entities	52,800	0
Other	11,000	15,300
Total deferred tax liabilities	271,500	278,700
Net deferred tax liabilities	(204,518)	(166,600)
Long-Term Contracts [Member]
Deferred tax liabilities:
Deferred income or gain	11,300	20,200
Equity Investee [Member]
Deferred tax liabilities:
Deferred income or gain	$ 6,900	$ 10,900

Income Taxes (Narrative) (Details) - USD ($)	3 Months Ended	12 Months Ended
Income Taxes (Narrative) (Details) - USD ($)	Dec. 31, 2017	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Income Taxes [Line Items]
Net deferred tax liabilities	$ 204,518,000		$ 204,518,000	$ 166,600,000
Deferred tax assets, net, current				11,800,000
Deferred tax liabilities, net, non-current				178,355,000
Valuation allowance, methodologies and assumptions			In assessing the ability to realize the deferred tax assets, management considers whether it is more likely than not that some portion or all of the deferred tax assets will not be realized. The ultimate realization of deferred tax assets is dependent upon the generation of future taxable income during the periods in which these temporary differences become deductible. Management considers the projected future taxable income and prudent and feasible tax planning strategies in making this assessment.
Net operating loss carryforwards	54,900,000		$ 54,900,000	$ 34,900,000
U.S. corporate tax rate, percent			35.00%	35.00%	35.00%
Change in enacted tax rate, non-cash tax benefit (in dollars)	120,100,000		$ 120,100,000
Provision for U.S. income taxes on unremitted foreign earnings	0		0
Unrecognized tax benefits	8,100,000		8,100,000	$ 0	$ 0	$ 0
Subsequent Event [Member]
Income Taxes [Line Items]
U.S. corporate tax rate, percent		21.00%
State [Member]
Income Taxes [Line Items]
Net operating loss carryforwards	12,300,000		$ 12,300,000	9,000,000
State [Member] \| Earliest Tax Year [Member]
Income Taxes [Line Items]
Net operating loss carryforwards, expiration date			Dec. 31, 2022
State [Member] \| Latest Tax Year [Member]
Income Taxes [Line Items]
Net operating loss carryforwards, expiration date			Dec. 31, 2037
Foreign [Member]
Income Taxes [Line Items]
Net operating loss carryforwards	38,400,000		$ 38,400,000	22,700,000
Foreign [Member] \| Earliest Tax Year [Member] \| Canada [Member]
Income Taxes [Line Items]
Net operating loss carryforwards, expiration date			Jan. 01, 2033
Federal [Member]
Income Taxes [Line Items]
Net operating loss carryforwards	$ 200,000		$ 200,000	$ 500,000
Federal [Member] \| Earliest Tax Year [Member]
Income Taxes [Line Items]
Net operating loss carryforwards, expiration date			Jan. 01, 2022

Income Taxes (Schedule of Effective Tax Rate Reconciliation) (Details)	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Income Tax Disclosure [Abstract]
U.S. statutory federal rate applied to pretax income (loss)	35.00%	35.00%	35.00%
State and local income taxes, net of federal benefit	2.00%	2.60%	(1.00%)
Foreign tax rate differential	0.30%	(0.10%)	(14.40%)
Non-deductible expenses	2.20%	4.40%	(13.50%)
Goodwill and intangible assets	(0.00%)	(0.70%)	(17.70%)
Change in tax rate	(32.30%)	(1.90%)	(3.60%)
Domestic production activities deduction	(0.20%)	(2.90%)	(1.00%)
Other	(0.70%)	(0.10%)	(1.40%)
Tax credits	(2.80%)	(0.00%)	(0.00%)
Valuation allowance for deferred tax assets	2.70%	4.30%	0.00%
Effective income tax rate	6.20%	40.60%	(17.60%)

Income Taxes (Rollforward of Uncertain Tax Positions) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Uncertain Tax Positions [Rollforward]
Uncertain tax positions, beginning balance	$ 0.0	$ 0.0	$ 0.0
Additions based on tax positions related to the current year	3.2	0.0	0.0
Additions for tax positions of prior years	4.9	0.0	0.0
Uncertain tax positions, ending balance	$ 8.1	$ 0.0	$ 0.0

Segments and Related Information (Narrative) (Details) $ in Thousands	3 Months Ended					12 Months Ended
	Mar. 31, 2017 USD ($)	Dec. 31, 2016 USD ($)	Sep. 30, 2016 USD ($)	Jun. 30, 2016 USD ($)	Mar. 31, 2016 USD ($)	Dec. 31, 2017 USD ($) segment	Dec. 31, 2016 USD ($)	Dec. 31, 2015 USD ($)
Segment and Related Information [Line Items]
Segment reporting information, factors used to identify entity's reportable segments						MasTec manages its operations under five operating segments, which represent MasTec’s five reportable segments: (1) Communications; (2) Oil and Gas; (3) Electrical Transmission; (4) Power Generation and Industrial and (5) Other. This structure is generally focused on broad end-user markets for MasTec’s labor-based construction services.
Number of operating segments \| segment						5
Number of reportable segments \| segment						5
Segment reporting information, description of products and services						All five reportable segments derive their revenue from the engineering, installation and maintenance of infrastructure, primarily in North America.
Segment reporting, description of all other segments						The Other segment includes equity investees, the services of which vary from those provided by the Company’s four primary segments, as well as other small business units that perform construction and other services for a variety of international end-markets.
Segment reporting, transactions between reportable segments						Intercompany revenue and costs among the reportable segments are de minimis and accounted for as if the sales were to third parties because these items are based on negotiated fees between the segments involved. All intercompany transactions and balances are eliminated in consolidation. Intercompany revenue and costs between entities within a reportable segment are eliminated to arrive at segment totals. Eliminations between segments are separately presented.
Segment reporting, additional information about entity's reportable segments						Segment results include certain allocations of centralized costs such as general liability, medical and workers’ compensation insurance and certain information technology costs. Income tax expense is managed by Corporate on a consolidated basis and is not allocated to the reportable segments.
Restructuring charges		$ 1,400	$ 4,700	$ 5,100	$ 4,100
Goodwill and intangible asset impairment (in dollars)						$ 0	$ 0	$ 78,625
General and administrative expenses						$ 275,103	261,433	265,910
Corporate [Member]
Segment and Related Information [Line Items]
Goodwill and intangible asset impairment (in dollars)								78,600
Corporate [Member] \| Audit Committee Investigation [Member]
Segment and Related Information [Line Items]
General and administrative expenses								16,500
Communications [Member]
Segment and Related Information [Line Items]
Segment reporting information, description of products and services						The Communications segment performs engineering, construction, maintenance and customer fulfillment activities related to communications infrastructure, primarily for wireless and wireline/fiber communications and install-to-the-home customers, and, to a lesser extent, infrastructure for utilities, among others.
Business combinations, acquisition integration costs (in dollars)								17,800
Oil and Gas [Member]
Segment and Related Information [Line Items]
Segment reporting information, description of products and services						MasTec performs engineering, construction and maintenance services on oil and natural gas pipelines and processing facilities for the energy and utilities industries through its Oil and Gas segment.
Restructuring charges							6,300
Oil and Gas [Member] \| Contracts Accounted for under Percentage-of-Completion [Member]
Segment and Related Information [Line Items]
Project losses (in dollars)							13,500
Electrical Transmission [Member]
Segment and Related Information [Line Items]
Segment reporting information, description of products and services						The Electrical Transmission segment primarily serves the energy and utility industries through the engineering, construction and maintenance of electrical transmission lines and substations.
Restructuring charges							8,900
Court mandated mediation settlement charge								12,200
Electrical Transmission [Member] \| Contracts Accounted for under Percentage-of-Completion [Member]
Segment and Related Information [Line Items]
Project losses (in dollars)							15,100
Power Generation and Industrial [Member]
Segment and Related Information [Line Items]
Segment reporting information, description of products and services						The Power Generation and Industrial segment primarily serves energy, utility and other end-markets through the installation and construction of conventional and renewable power facilities, related electrical transmission infrastructure, ethanol/biofuel facilities and various types of heavy civil and industrial infrastructure.
Power Generation and Industrial [Member] \| Contracts Accounted for under Percentage-of-Completion [Member]
Segment and Related Information [Line Items]
Project losses (in dollars)								21,400
Primary Segments [Member]
Segment and Related Information [Line Items]
Number of operating segments \| segment						4
Other [Member] \| Contracts Accounted for under Percentage-of-Completion [Member] \| Pacer [Member] \| Joint Venture [Member] \| Canadian Dollars [Member]
Segment and Related Information [Line Items]
Project losses (in dollars)	$ 7,000		$ 5,100			$ 7,900	$ 5,100	$ 16,300

Segments and Related Information (Schedule of Financial Information by Reportable Segment - Revenue) (Details) - USD ($)
$ in Thousands

3 Months Ended

12 Months Ended

Dec. 31, 2017

Sep. 30, 2017

Jun. 30, 2017

Mar. 31, 2017

Dec. 31, 2016

Sep. 30, 2016

Jun. 30, 2016

Mar. 31, 2016

Dec. 31, 2017

Dec. 31, 2016

Dec. 31, 2015

Revenue:

Communications [Member] | Customer Concentration Risk [Member] | Revenue [Member] | Utilities [Member]

$ 1,602,900

$ 1,955,800

$ 1,890,200

$ 1,158,200

$ 1,341,900

$ 1,586,200

$ 1,232,400

$ 974,200

$ 6,606,978

$ 5,134,703

$ 4,208,330

Revenue:

Utilities customers, percentage of Communications segment revenue

13.40%

11.10%

10.60%

Reportable Segments [Member] | Communications [Member]

Revenue:

Reportable Segments [Member] | Oil and Gas [Member]

^[1]

$ 2,424,400

$ 2,323,600

$ 1,973,200

Revenue:

Reportable Segments [Member] | Electrical Transmission [Member]

3,497,200

2,024,400

1,495,100

Revenue:

Reportable Segments [Member] | Power Generation and Industrial [Member]

378,200

383,800

341,500

Revenue:

Reportable Segments [Member] | Other [Member]

299,900

405,700

381,600

Revenue:

20,800

15,900

24,100

Eliminations [Member]

Revenue:

Oil and Gas [Member] | Energy Transfer Affiliates [Member]

$ (13,500)

$ (18,700)

$ (7,200)

[1]	Revenue generated primarily by utilities customers represented 13.4%, 11.1% and 10.6% of Communications segment revenue for the years ended December 31, 2017, 2016 and 2015, respectively.

Segments and Related Information (Schedule of Financial Information by Reportable Segment - EBITDA) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
EBITDA:
EBITDA	$ 620.9	$ 441.5	$ 150.0
Reportable Segments [Member] \| Communications [Member]
EBITDA:
EBITDA	247.4	244.6	194.8
Reportable Segments [Member] \| Oil and Gas [Member]
EBITDA:
EBITDA	402.2	297.3	157.0
Reportable Segments [Member] \| Electrical Transmission [Member]
EBITDA:
EBITDA	17.6	(42.9)	(71.3)
Reportable Segments [Member] \| Power Generation and Industrial [Member]
EBITDA:
EBITDA	22.6	18.3	8.8
Reportable Segments [Member] \| Other [Member]
EBITDA:
EBITDA	19.8	(2.6)	(18.8)
Corporate [Member]
EBITDA:
EBITDA	$ (88.7)	$ (73.1)	$ (120.5)

Segments and Related Information (Schedule of Financial Information by Reportable Segment - Depreciation and Amortization) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Depreciation and Amortization:
Depreciation and amortization	$ 188,049	$ 164,915	$ 169,662
Reportable Segments [Member] \| Communications [Member]
Depreciation and Amortization:
Depreciation and amortization	53,200	50,300	50,600
Reportable Segments [Member] \| Oil and Gas [Member]
Depreciation and Amortization:
Depreciation and amortization	96,700	78,400	84,500
Reportable Segments [Member] \| Electrical Transmission [Member]
Depreciation and Amortization:
Depreciation and amortization	22,800	23,200	21,100
Reportable Segments [Member] \| Power Generation and Industrial [Member]
Depreciation and Amortization:
Depreciation and amortization	9,100	6,200	6,600
Reportable Segments [Member] \| Other [Member]
Depreciation and Amortization:
Depreciation and amortization	100	100	100
Corporate [Member]
Depreciation and Amortization:
Depreciation and amortization	$ 6,100	$ 6,700	$ 6,800

Segments and Related Information (Schedule of Financial Information by Reportable Segment - Assets) (Details) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Assets:
Assets	$ 4,066,576	$ 3,183,132	$ 2,927,300
Reportable Segments [Member] \| Communications [Member]
Assets:
Assets	1,314,400	1,156,900	1,032,200
Reportable Segments [Member] \| Oil and Gas [Member]
Assets:
Assets	1,762,600	1,267,200	1,131,400
Reportable Segments [Member] \| Electrical Transmission [Member]
Assets:
Assets	471,400	419,100	409,100
Reportable Segments [Member] \| Power Generation and Industrial [Member]
Assets:
Assets	288,600	268,100	252,500
Reportable Segments [Member] \| Other [Member]
Assets:
Assets	153,200	27,700	34,300
Corporate [Member]
Assets:
Assets	$ 76,400	$ 44,100	$ 67,800

Segments and Related Information (Schedule of Financial Information by Reportable Segment - Capital Expenditures) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Capital Expenditures:
Capital expenditures	$ 123,412	$ 117,114	$ 84,410
Reportable Segments [Member] \| Communications [Member]
Capital Expenditures:
Capital expenditures	40,500	28,500	25,800
Reportable Segments [Member] \| Oil and Gas [Member]
Capital Expenditures:
Capital expenditures	57,700	64,000	38,100
Reportable Segments [Member] \| Electrical Transmission [Member]
Capital Expenditures:
Capital expenditures	14,900	19,800	13,000
Reportable Segments [Member] \| Power Generation and Industrial [Member]
Capital Expenditures:
Capital expenditures	5,400	3,400	3,500
Reportable Segments [Member] \| Other [Member]
Capital Expenditures:
Capital expenditures	0	300	200
Corporate [Member]
Capital Expenditures:
Capital expenditures	$ 4,900	$ 1,100	$ 3,800

Segments and Related Information (Reconciliation of Consolidated Income (Loss) before Income Taxes to EBITDA) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
EBITDA Reconciliation:
Income (loss) before income taxes	$ 371,826	$ 225,819	$ (67,746)
Interest expense, net	61,011	50,734	48,055
Depreciation and amortization	188,049	164,915	169,662
EBITDA	$ 620,900	$ 441,500	$ 150,000

Segments and Related Information (Foreign Operations) (Narrative) (Details) - USD ($) $ in Thousands				3 Months Ended								12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Segment and Related Information [Line Items]
Revenue				$ 1,602,900	$ 1,955,800	$ 1,890,200	$ 1,158,200	$ 1,341,900	$ 1,586,200	$ 1,232,400	$ 974,200	$ 6,606,978	$ 5,134,703	$ 4,208,330
Property and equipment, net	$ 706,506	$ 549,084		706,506				549,084				706,506	549,084
Intangible assets and goodwill, net	1,328,900	1,175,600		1,328,900				1,175,600				1,328,900	1,175,600
United States [Member]
Segment and Related Information [Line Items]
Revenue												6,400,000	4,900,000	3,600,000
Property and equipment, net	649,500	475,300	$ 464,600	649,500				475,300				649,500	475,300	464,600
Intangible assets and goodwill, net	1,200,000	1,100,000	1,100,000	1,200,000				1,100,000				1,200,000	1,100,000	1,100,000
Foreign Operations [Member]
Segment and Related Information [Line Items]
Revenue												211,500	279,700	574,800
Property and equipment, net	57,000	73,800	94,100	57,000				73,800				57,000	73,800	94,100
Intangible assets and goodwill, net	$ 112,800	$ 107,800	$ 107,300	$ 112,800				$ 107,800				$ 112,800	$ 107,800	$ 107,300
Foreign Operations [Member] \| Accounts Receivable, Net, Less BIEC [Member] \| Geographic Concentration Risk [Member] \| Foreign Customers [Member]
Segment and Related Information [Line Items]
Concentration risk, percentage of total	5.00%	8.00%	17.00%

Segments and Related Information (Schedule of Significant Customers, Revenue Concentration Information) (Details) - Customer Concentration Risk [Member] - Revenue [Member]

12 Months Ended

Dec. 31, 2017

Dec. 31, 2016

Dec. 31, 2015

Revenue, Significant Customer [Line Items]

Concentration risk, percentage of total

^[1]

40.00%

27.00%

7.00%

Communications [Member] | AT&T (including DIRECTV) [Member]

Revenue, Significant Customer [Line Items]

Concentration risk, percentage of total

^[2]

25.00%

34.00%

32.00%

[1]

The Company's relationship with Energy Transfer affiliates is based upon various construction contracts for pipeline activities with Energy Transfer Partners L.P., and its subsidiaries and affiliates, all of which are consolidated by Energy Transfer Equity, L.P. Revenue from Energy Transfer affiliates is included in the Oil and Gas segment.

[2]

Commitments and Contingencies (Other Commitments and Contingencies) (Narrative) (Details) - USD ($) $ in Millions	Dec. 31, 2017	Dec. 31, 2016
Self-Insurance [Member] \| Workers' Compensation, General and Automobile Policies [Member]
Loss Contingencies [Line Items]
Self-insurance reserve	$ 106.2	$ 85.8
Self-Insurance [Member] \| Workers' Compensation, General and Automobile Policies [Member] \| Other Long-Term Liabilities [Member]
Loss Contingencies [Line Items]
Self-insurance reserve, non-current	72.2	55.2
Self-Insurance [Member] \| Workers' Compensation, General and Automobile Policies [Member] \| Other Long-Term Assets [Member] \| Cash [Member]
Loss Contingencies [Line Items]
Cash collateral held by insurance carriers	1.6	1.5
Self-Insurance [Member] \| Employee Group Medical Claims Policy [Member]
Loss Contingencies [Line Items]
Self-insurance reserve	2.6	2.6
Performance and Payment Bonds [Member] \| Estimate [Member]
Loss Contingencies [Line Items]
Bonded projects, costs to complete	46.0	9.5
Performance and Payment Bonds [Member] \| Subsidiaries [Member]
Loss Contingencies [Line Items]
Outstanding bonds, amount	119.7	72.9
Surety Bonds [Member] \| Self-Insurance [Member] \| Workers' Compensation [Member]
Loss Contingencies [Line Items]
Outstanding bonds, amount	15.2	13.5
Credit Facility [Member]
Loss Contingencies [Line Items]
Letters of credit issued	157.1	314.3
Credit Facility [Member] \| Financial Guarantees [Member] \| Self-Insurance [Member] \| Workers' Compensation, General and Automobile Policies [Member]
Loss Contingencies [Line Items]
Letters of credit issued	$ 88.9	$ 85.1

Commitments and Contingencies (Investment Arrangements) (Narrative) (Details) - Joint Venture [Member]	Dec. 31, 2017
Pacer [Member]
Other Commitments [Line Items]
Proportionately consolidated non-controlled joint venture, ownership percentage	35.00%
Joint Ventures That Provide Electrical Transmission Infrastructure Services [Member] \| Minimum [Member]
Other Commitments [Line Items]
Proportionately consolidated non-controlled joint venture, ownership percentage	85.00%
Joint Ventures That Provide Electrical Transmission Infrastructure Services [Member] \| Maximum [Member]
Other Commitments [Line Items]
Proportionately consolidated non-controlled joint venture, ownership percentage	90.00%

Commitments and Contingencies (Collective Bargaining Agreements and Multiemployer Plans) (Narrative) (Details) - Central States [Member] - Multiemployer Plans, Pension [Member] - USD ($) $ in Millions	12 Months Ended	72 Months Ended
	Dec. 31, 2017	Dec. 31, 2017	Dec. 31, 2011
Loss Contingencies [Line Items]
Multiemployer plan, withdrawal liability, amount			$ 6.4
Multiemployer plan, withdrawal liability, payments		$ 6.4
Multiemployer plan, withdrawal liability, expense	$ 0.7

Commitments and Contingencies (Other Guarantees) (Narrative) (Details)	12 Months Ended
	Dec. 31, 2017
Other Guarantees [Line Items]
General warranty, description	MasTec also generally warrants the work it performs for a one to two year period following substantial completion of a project.
Warranty [Member] \| Minimum [Member]
Other Guarantees [Line Items]
General warranty, period (in years)	1 year
Warranty [Member] \| Maximum [Member]
Other Guarantees [Line Items]
General warranty, period (in years)	2 years
Subsidiaries [Member]
Other Guarantees [Line Items]
Other guarantees, description	In the ordinary course of its business, from time to time, MasTec guarantees the obligations of its subsidiaries, including obligations under certain contracts with customers, certain lease obligations and in some states, obligations in connection with obtaining contractors’ licenses.

Commitments and Contingencies (Concentrations of Risk) (Narrative) (Details) - customer			12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Concentration Risk [Line Items]
Number of customers			500
Accounts Receivable, Net, Less BIEC [Member] \| Credit Concentration Risk [Member] \| Customer with Highest Net Accounts Receivable Position [Member]
Concentration Risk [Line Items]
Number of customers	1	1
Concentration risk, percentage of total	46.00%	24.00%
Accounts Receivable, Net, Less BIEC [Member] \| Credit Concentration Risk [Member] \| Customer With Second Highest Net Accounts Receivable Position [Member]
Concentration Risk [Line Items]
Concentration risk, percentage of total	15.00%	17.00%
Revenue [Member] \| Customer Concentration Risk [Member] \| Ten Largest Customers [Member]
Concentration Risk [Line Items]
Number of customers			10	10	10
Concentration risk, percentage of total			78.00%	76.00%	61.00%

Related Party Transactions (Equity Method Investment) (Narrative) (Details) - 2017 Acquisitions [Member]	12 Months Ended
	Dec. 31, 2017 USD ($)
Equity Method Investee [Member]
Related Party Transaction [Line Items]
Equity investment, ownership percentage	40.00%
Equity investment, value	$ 400,000
Financing or amounts advanced, related party	300,000
Equity investment, amounts outstanding	300,000
Equity Method Investee [Member] \| Subcontracting Arrangements [Member]
Related Party Transaction [Line Items]
Expenses, related party	200,000
Payables, related party	0
Management [Member] \| Financing Arrangements [Member]
Related Party Transaction [Line Items]
Expenses, related party	5,300,000
Payables, related party	$ 0

Related Party Transactions (CCI) (Narrative) (Details) - CCI [Member] - Immediate Family Member of Management [Member] - Equipment [Member] - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Related Party Transaction [Line Items]
Payments, related party	$ 54.9	$ 24.5	$ 10.6
Payables, related party	$ 2.7	$ 1.5

Related Party Transactions (Subcontracting Arrangements) (Narrative) (Details) - Related Contractor Or Supplier [Member] - Management [Member] $ in Millions	12 Months Ended
	Dec. 31, 2017 USD ($) employee	Dec. 31, 2016 USD ($)
Subcontracting Arrangements [Member]
Related Party Transaction [Line Items]
Number of additional management employees, subcontracting arrangement \| employee	2
Expenses, related party	$ 78.0	$ 12.9
Payables, related party	$ 2.0	0.1
Equipment [Member]
Related Party Transaction [Line Items]
Proceeds from sale of equipment, related party		$ 0.3

Related Party Transactions (Leases and Other Transactions) (Narrative) (Details) - USD ($)	1 Months Ended	3 Months Ended	12 Months Ended
	Feb. 27, 2018	Sep. 30, 2017	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Earn-Out Liabilities [Member]
Related Party Transaction [Line Items]
Additions to acquisition-related contingent consideration			$ 102,534,000	$ 0	$ 0
Executive Officers [Member] \| Employee Leasing Arrangements [Member] \| Related Customer [Member]
Related Party Transaction [Line Items]
Charges, related party			800,000	800,000	800,000
Receivables, related party			200,000	200,000
Executive Officers [Member] \| Services [Member] \| Related Customer [Member]
Related Party Transaction [Line Items]
Revenue, related party			800,000	900,000	900,000
Receivables, related party			300,000	400,000
Immediate Family Member of Management [Member] \| Construction Management Firm Specializing in Steel Building Systems [Member] \| Subsequent Event [Member]
Related Party Transaction [Line Items]
Cash paid, business combination	$ 5,000,000
Immediate Family Member of Management [Member] \| Property Lease [Member]
Related Party Transaction [Line Items]
Payments, related party			48,000	48,000	48,000
Chairman, Board of Directors [Member] \| Lease Agreements [Member] \| Aircraft [Member]
Related Party Transaction [Line Items]
Payments, related party			2,000,000	2,600,000
Management [Member] \| Oil and Gas 2017 Acquisition [Member]
Related Party Transaction [Line Items]
Cash paid, business combination		$ 40,600,000
Management [Member] \| Oil and Gas 2017 Acquisition [Member] \| Earn-Out Liabilities [Member]
Related Party Transaction [Line Items]
Additions to acquisition-related contingent consideration		$ 57,200,000
Management [Member] \| Services [Member]
Related Party Transaction [Line Items]
Payments, related party			63,900,000	27,700,000	10,500,000
Payables, related party			5,200,000	3,700,000
Management [Member] \| Lease Agreements [Member]
Related Party Transaction [Line Items]
Payments, related party			46,800,000	43,300,000	$ 22,100,000
Payables, related party			100,000	$ 300,000
Management [Member] \| Construction Contracts [Member]
Related Party Transaction [Line Items]
Revenue, related party			2,600,000
Receivables, related party			$ 600,000

Related Party Transactions (Contractual Joint Venture) (Narrative) (Details) - Joint Venture [Member] - Pacer [Member] $ in Millions	12 Months Ended
	Dec. 31, 2017 USD ($)	Dec. 31, 2016 USD ($)	Dec. 31, 2015 USD ($)	Dec. 31, 2017 CAD ($)	Dec. 31, 2016 CAD ($)
Related Party Transaction [Line Items]
Joint venture, ownership percentage	35.00%			35.00%
Construction projects, percentage complete	90.00%			90.00%
Performance Guarantees [Member]
Related Party Transaction [Line Items]
Guarantees issued, related party				$ 132.1	$ 132.1
Canadian Dollars [Member]
Related Party Transaction [Line Items]
Revenue, related party	$ 1,500,000	$ 1,000,000	$ 2,100,000
Canadian Dollars [Member] \| Financial Support [Member]
Related Party Transaction [Line Items]
Financing or amounts advanced, related party	7,200,000	6,800,000
Amounts committed, related party	0
Canadian Dollars [Member] \| Performance Guarantees [Member]
Related Party Transaction [Line Items]
Guarantees issued, related party	105,100,000	98,300,000
Canadian Dollars [Member] \| Accounts Receivable, Net of Billings in Excess of Costs [Member]
Related Party Transaction [Line Items]
Receivables, related party	$ 800,000	$ 700,000

Related Party Transactions (Non-Controlling Interests) (Narrative) (Details) $ in Thousands	1 Months Ended	3 Months Ended	12 Months Ended
	Oct. 31, 2017 USD ($)	Mar. 31, 2018 USD ($)	Dec. 31, 2017 USD ($)	Dec. 31, 2016 USD ($)	Dec. 31, 2015 USD ($)
Related Party Transaction [Line Items]
Distributions to non-controlling interests			$ 22,728	$ 0	$ 0
Earn-Out Liabilities [Member]
Related Party Transaction [Line Items]
Fair value of contingent consideration (earn-out liability)			102,534	$ 0	$ 0
Management [Member]
Related Party Transaction [Line Items]
Payments for acquisition of non-controlling interests	$ 21,400
Distributions to non-controlling interests			$ 1,300
Management [Member] \| Forecast [Member]
Related Party Transaction [Line Items]
Distributions to non-controlling interests		$ 600
Management [Member] \| Subcontracting Arrangements [Member]
Related Party Transaction [Line Items]
Non-controlling interests, number of subsidiaries,			1
Management [Member] \| Acquisition of Non-Controlling Interest [Member]
Related Party Transaction [Line Items]
Non-controlling interests, number of subsidiaries,	1
Management [Member] \| Acquisition of Non-Controlling Interest [Member] \| Earn-Out Liabilities [Member]
Related Party Transaction [Line Items]
Fair value of contingent consideration (earn-out liability)	$ 9,000

Related Party Transactions (Split Dollar Agreements) (Narrative) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015	Feb. 27, 2018
Chairman, Board of Directors [Member]
Related Party Transaction [Line Items]
Payments for life insurance policies	$ 1.1	$ 1.1	$ 1.1
Chairman, Board of Directors [Member] \| Maximum [Member]
Related Party Transaction [Line Items]
Life insurance, face amount	200.0
Chairman, Board of Directors [Member] \| Maximum [Member] \| Subsequent Event [Member]
Related Party Transaction [Line Items]
Life insurance, face amount				$ 200.0
Chief Executive Officer [Member]
Related Party Transaction [Line Items]
Payments for life insurance policies	0.7	0.7	$ 0.7
Chief Executive Officer [Member] \| Maximum [Member]
Related Party Transaction [Line Items]
Life insurance, face amount	75.0
Chief Executive Officer [Member] \| Maximum [Member] \| Subsequent Event [Member]
Related Party Transaction [Line Items]
Life insurance, face amount				$ 75.0
Executive Officers [Member] \| Other Long-Term Assets [Member]
Related Party Transaction [Line Items]
Life insurance assets, carrying amount	$ 16.6	$ 14.8

Quarterly Information (Unaudited) (Schedule of Quarterly Financial Information (Unaudited)) (Details) - USD ($)
$ / shares in Units, $ in Thousands

3 Months Ended

12 Months Ended

Dec. 31, 2017

Sep. 30, 2017

Jun. 30, 2017

Mar. 31, 2017

Dec. 31, 2016

Sep. 30, 2016

Jun. 30, 2016

Mar. 31, 2016

Dec. 31, 2017

Dec. 31, 2016

Dec. 31, 2015

Selected Quarterly Financial Information [Abstract]

Costs of revenue, excluding depreciation and amortization

$ 1,602,900

$ 1,955,800

$ 1,890,200

$ 1,158,200

$ 1,341,900

$ 1,586,200

$ 1,232,400

$ 974,200

$ 6,606,978

$ 5,134,703

$ 4,208,330

1,421,700

1,726,200

1,626,300

971,100

1,120,600

1,369,000

1,068,200

884,400

5,745,307

4,442,125

3,721,303

160,700

64,200

83,300

40,600

55,900

56,500

24,400

(2,900)

348,884

134,035

(79,703)

Basic (in dollars per share)

$ 160,800

$ 63,800

$ 81,700

$ 41,000

$ 53,600

$ 56,300

$ 24,100

$ (2,700)

$ 347,213

^[1]

$ 131,263

^[1]

$ (79,110)

^[1]

Earnings (loss) per share:

$ 1.98

$ 0.79

$ 1.01

$ 0.51

$ 0.67

$ 0.70

$ 0.30

$ (0.03)

$ 4.29

$ 1.63

$ (0.98)

Diluted (in dollars per share)

$ 1.95

$ 0.77

$ 0.99

$ 0.50

$ 0.66

$ 0.69

$ 0.30

$ (0.03)

$ 4.22

$ 1.61

$ (0.98)

[1]	Calculated as total net income (loss) less amounts attributable to non-controlling interests.

Quarterly Information (Unaudited) (Narrative) (Details) - USD ($) $ in Thousands	3 Months Ended						12 Months Ended
	Dec. 31, 2017	Mar. 31, 2017	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Quarterly Financial Information [Line Items]
Tax benefit, net							$ (22,942)	$ (91,784)	$ (11,957)
Change in enacted tax rate, non-cash tax benefit	$ 120,100						120,100
Restructuring charges			$ 1,400	$ 4,700	$ 5,100	$ 4,100
Share-Based Compensation [Member]
Quarterly Financial Information [Line Items]
Tax benefit, net	$ 5,600						5,400
Contracts Accounted for under Percentage-of-Completion [Member] \| Canadian Dollars [Member] \| Joint Venture [Member] \| Pacer [Member] \| Other [Member]
Quarterly Financial Information [Line Items]
Project losses		$ 7,000		$ 5,100			$ 7,900	$ 5,100	$ 16,300

Supplemental Guarantor Financial Information (Narrative) (Details)	Dec. 31, 2017
Senior Notes [Member] \| 4.875% Senior Notes [Member]
Condensed Financial Statements, Captions [Line Items]
Debt instrument, interest rate (percentage)	4.875%

Supplemental Guarantor Financial Information (Condensed Consolidating Statements of Operations and Comprehensive Income (Loss)) (Details) - USD ($)
$ in Thousands

3 Months Ended

12 Months Ended

Dec. 31, 2017

Sep. 30, 2017

Jun. 30, 2017

Mar. 31, 2017

Dec. 31, 2016

Sep. 30, 2016

Jun. 30, 2016

Mar. 31, 2016

Dec. 31, 2017

Dec. 31, 2016

Dec. 31, 2015

Condensed Consolidating Statements of Operations and Comprehensive Income (Loss) [Line Items]

Costs of revenue, excluding depreciation and amortization

$ 1,602,900

$ 1,955,800

$ 1,890,200

$ 1,158,200

$ 1,341,900

$ 1,586,200

$ 1,232,400

$ 974,200

$ 6,606,978

$ 5,134,703

$ 4,208,330

1,421,700

1,726,200

1,626,300

971,100

1,120,600

1,369,000

1,068,200

884,400

5,745,307

4,442,125

3,721,303

188,049

164,915

169,662

78,625

275,103

261,433

265,910

Equity in (earnings) losses of unconsolidated affiliates

61,011

50,734

48,055

(21,328)

(3,528)

7,978

(12,990)

(6,795)

(15,457)

371,826

225,819

(67,746)

Net income (loss) before equity in income (loss) from subsidiaries

(22,942)

(91,784)

(11,957)

348,900

134,000

(79,700)

Equity in income (losses) from subsidiaries, net of tax

Net income (loss) attributable to non-controlling interests

160,700

64,200

83,300

40,600

55,900

56,500

24,400

(2,900)

348,884

134,035

(79,703)

1,671

2,772

(593)

$ 160,800

$ 63,800

$ 81,700

$ 41,000

$ 53,600

$ 56,300

$ 24,100

$ (2,700)

347,213

^[1]

131,263

^[1]

(79,110)

^[1]

Reportable Legal Entities [Member] | MasTec, Inc. [Member]

350,986

140,572

(118,050)

Condensed Consolidating Statements of Operations and Comprehensive Income (Loss) [Line Items]

Costs of revenue, excluding depreciation and amortization

2,300

2,400

2,100

Equity in (earnings) losses of unconsolidated affiliates

(2,300)

(2,400)

(2,100)

Net income (loss) before equity in income (loss) from subsidiaries

200

900

1,100

(2,100)

(1,500)

(1,000)

Equity in income (losses) from subsidiaries, net of tax

349,300

132,800

(78,100)

Net income (loss) attributable to non-controlling interests

347,200

131,300

(79,100)

347,200

131,300

(79,100)

Reportable Legal Entities [Member] | Guarantor Subsidiaries [Member]

349,300

137,800

(117,500)

Condensed Consolidating Statements of Operations and Comprehensive Income (Loss) [Line Items]

Costs of revenue, excluding depreciation and amortization

6,222,300

4,790,900

3,527,000

5,378,600

4,101,200

3,073,600

159,100

134,200

130,600

256,300

234,400

235,400

Equity in (earnings) losses of unconsolidated affiliates

123,600

112,000

111,000

(13,000)

(6,200)

317,700

209,100

(17,400)

Net income (loss) before equity in income (loss) from subsidiaries

(18,100)

(72,600)

9,300

299,600

136,500

(8,100)

Equity in income (losses) from subsidiaries, net of tax

Net income (loss) attributable to non-controlling interests

299,600

136,500

(8,100)

2,400

3,300

297,200

133,200

(8,100)

Reportable Legal Entities [Member] | Non-Guarantor Subsidiaries [Member]

299,600

136,500

(8,100)

Condensed Consolidating Statements of Operations and Comprehensive Income (Loss) [Line Items]

Costs of revenue, excluding depreciation and amortization

457,000

353,800

689,700

439,000

350,900

656,100

28,900

30,700

39,100

78,600

16,500

24,600

28,400

Equity in (earnings) losses of unconsolidated affiliates

(62,600)

(61,300)

(62,900)

(21,300)

(3,500)

8,000

(6,800)

(9,300)

56,500

19,200

(48,300)

Net income (loss) before equity in income (loss) from subsidiaries

(5,000)

(20,100)

(22,300)

51,500

(900)

(70,600)

Equity in income (losses) from subsidiaries, net of tax

Net income (loss) attributable to non-controlling interests

51,500

(900)

(70,600)

(700)

(500)

(600)

52,200

(400)

(70,000)

Condensed Consolidating Statements of Operations and Comprehensive Income (Loss) [Line Items]

53,600

5,600

(109,000)

Eliminations [Member]

Costs of revenue, excluding depreciation and amortization

(72,300)

(10,000)

(8,400)

(72,300)

(10,000)

(8,400)

Equity in (earnings) losses of unconsolidated affiliates

Net income (loss) before equity in income (loss) from subsidiaries

Equity in income (losses) from subsidiaries, net of tax

(349,300)

(132,800)

78,100

Net income (loss) attributable to non-controlling interests

(349,300)

(132,800)

78,100

(349,300)

(132,800)

78,100

Valuation and Qualifying Accounts [Roll Forward]

$ (351,400)

$ (139,300)

$ 116,500

[1]	Calculated as total net income (loss) less amounts attributable to non-controlling interests.

Supplemental Guarantor Financial Information (Condensed Consolidating Balance Sheets) (Details) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Assets
Total current assets	$ 1,852,366	$ 1,402,486
Property and equipment, net	706,506	549,084
Goodwill and other intangible assets, net	1,328,900	1,175,600
Investments in and advances to consolidated affiliates, net	0	0
Other long-term assets	178,824	55,977
Total assets	4,066,576	3,183,132	$ 2,927,300
Liabilities and equity
Total current liabilities	963,827	839,990
Long-term debt	1,280,706	961,379
Other long-term liabilities	388,700	278,100
Total liabilities	2,633,223	2,079,498
Total equity	1,433,353	1,103,634	$ 943,391	$ 1,148,075
Total liabilities and equity	4,066,576	3,183,132
Reportable Legal Entities [Member] \| MasTec, Inc. [Member]
Assets
Total current assets	0	0
Property and equipment, net	0	0
Goodwill and other intangible assets, net	0	0
Investments in and advances to consolidated affiliates, net	1,415,000	1,083,900
Other long-term assets	15,800	12,600
Total assets	1,430,800	1,096,500
Liabilities and equity
Total current liabilities	0	0
Long-term debt	0	0
Other long-term liabilities	0	0
Total liabilities	0	0
Total equity	1,430,800	1,096,500
Total liabilities and equity	1,430,800	1,096,500
Reportable Legal Entities [Member] \| Guarantor Subsidiaries [Member]
Assets
Total current assets	1,536,600	1,257,200
Property and equipment, net	638,700	463,700
Goodwill and other intangible assets, net	1,187,900	1,037,400
Investments in and advances to consolidated affiliates, net	847,700	617,400
Other long-term assets	23,400	25,200
Total assets	4,234,300	3,400,900
Liabilities and equity
Total current liabilities	778,600	742,800
Long-term debt	1,269,400	941,700
Other long-term liabilities	379,900	258,100
Total liabilities	2,427,900	1,942,600
Total equity	1,806,400	1,458,300
Total liabilities and equity	4,234,300	3,400,900
Reportable Legal Entities [Member] \| Non-Guarantor Subsidiaries [Member]
Assets
Total current assets	332,900	155,500
Property and equipment, net	67,800	85,400
Goodwill and other intangible assets, net	141,000	138,200
Investments in and advances to consolidated affiliates, net	746,600	867,700
Other long-term assets	139,600	18,100
Total assets	1,427,900	1,264,900
Liabilities and equity
Total current liabilities	202,300	107,400
Long-term debt	11,300	19,700
Other long-term liabilities	8,800	20,000
Total liabilities	222,400	147,100
Total equity	1,205,500	1,117,800
Total liabilities and equity	1,427,900	1,264,900
Eliminations [Member]
Assets
Total current assets	(17,100)	(10,200)
Property and equipment, net	0	0
Goodwill and other intangible assets, net	0	0
Investments in and advances to consolidated affiliates, net	(3,009,300)	(2,569,000)
Other long-term assets	0	0
Total assets	(3,026,400)	(2,579,200)
Liabilities and equity
Total current liabilities	(17,100)	(10,200)
Long-term debt	0	0
Other long-term liabilities	0	0
Total liabilities	(17,100)	(10,200)
Total equity	(3,009,300)	(2,569,000)
Total liabilities and equity	$ (3,026,400)	$ (2,579,200)

Supplemental Guarantor Financial Information (Condensed Consolidating Statements of Cash Flows) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Condensed Consolidating Statements of Cash Flows [Line Items]
Net cash provided by (used in) operating activities	$ 156,263	$ 205,593	$ 367,413
Cash flows from investing activities:
Cash paid for acquisitions, net of cash acquired	(115,995)	(4,102)	(148)
Capital expenditures	(123,412)	(117,114)	(84,410)
Proceeds from sale of property and equipment	19,963	11,239	13,932
Payments for other investments	(77,105)	(32,169)	(127,480)
Proceeds from other investments	23,801	1,125	69,406
Net cash used in investing activities	(272,748)	(141,021)	(128,700)
Cash flows from financing activities:
Proceeds from credit facilities	2,699,047	1,681,424	1,702,431
Repayments of credit facilities	(2,457,293)	(1,627,129)	(1,742,077)
Repayments of other borrowings and capital lease obligations, net	(71,100)	(68,700)	(70,900)
Payments of acquisition-related contingent consideration	(18,843)	(19,822)	(47,523)
Payments to non-controlling interests, including acquisition of interests and distributions	(22,728)	0	0
(Payments for) proceeds from stock-based awards, net	(3,085)	4,200	1,566
Repurchase of common stock	(1,552)	0	(100,000)
Other financing activities, net	(6,301)	515	(2,379)
Net financing activities and advances from (to) consolidated affiliates	0	0	0
Net cash provided by (used in) financing activities	118,155	(29,486)	(258,920)
Effect of currency translation on cash	(111)	(1,303)	1,132
Net increase (decrease) in cash and cash equivalents	1,559	33,783	(19,075)
Cash and cash equivalents - beginning of period	38,767	4,984	24,059
Cash and cash equivalents - end of period	40,326	38,767	4,984
Reportable Legal Entities [Member] \| MasTec, Inc. [Member]
Condensed Consolidating Statements of Cash Flows [Line Items]
Net cash provided by (used in) operating activities	0	0	900
Cash flows from investing activities:
Cash paid for acquisitions, net of cash acquired	0	0	0
Capital expenditures	0	0	0
Proceeds from sale of property and equipment	0	0	0
Payments for other investments	0	0	(1,900)
Proceeds from other investments	0	0	0
Net cash used in investing activities	0	0	(1,900)
Cash flows from financing activities:
Proceeds from credit facilities	0	0	0
Repayments of credit facilities	0	0	0
Repayments of other borrowings and capital lease obligations, net	0	0	0
Payments of acquisition-related contingent consideration	0	0	0
Payments to non-controlling interests, including acquisition of interests and distributions	0
(Payments for) proceeds from stock-based awards, net	(3,100)	4,200	2,700
Repurchase of common stock	(1,600)		(100,000)
Other financing activities, net	0	100	0
Net financing activities and advances from (to) consolidated affiliates	4,700	(4,300)	98,300
Net cash provided by (used in) financing activities	0	0	1,000
Effect of currency translation on cash	0	0	0
Net increase (decrease) in cash and cash equivalents	0	0	0
Cash and cash equivalents - beginning of period	0	0	0
Cash and cash equivalents - end of period	0	0	0
Reportable Legal Entities [Member] \| Guarantor Subsidiaries [Member]
Condensed Consolidating Statements of Cash Flows [Line Items]
Net cash provided by (used in) operating activities	155,100	130,500	358,500
Cash flows from investing activities:
Cash paid for acquisitions, net of cash acquired	(116,000)	(4,100)	(100)
Capital expenditures	(120,100)	(112,600)	(71,900)
Proceeds from sale of property and equipment	18,200	7,600	10,500
Payments for other investments	(3,800)	(3,900)	0
Proceeds from other investments	1,200	0	0
Net cash used in investing activities	(220,500)	(113,000)	(61,500)
Cash flows from financing activities:
Proceeds from credit facilities	2,674,400	1,553,400	1,097,300
Repayments of credit facilities	(2,428,900)	(1,496,600)	(1,154,300)
Repayments of other borrowings and capital lease obligations, net	(61,500)	(50,400)	(54,300)
Payments of acquisition-related contingent consideration	(18,800)	(16,600)	(37,300)
Payments to non-controlling interests, including acquisition of interests and distributions	(22,700)
(Payments for) proceeds from stock-based awards, net	0	0	(1,100)
Repurchase of common stock	0		0
Other financing activities, net	(6,300)	400	(2,400)
Net financing activities and advances from (to) consolidated affiliates	(89,600)	16,400	(158,600)
Net cash provided by (used in) financing activities	46,600	6,600	(310,700)
Effect of currency translation on cash	0	0	0
Net increase (decrease) in cash and cash equivalents	(18,800)	24,100	(13,700)
Cash and cash equivalents - beginning of period	28,900	4,800	18,500
Cash and cash equivalents - end of period	10,100	28,900	4,800
Reportable Legal Entities [Member] \| Non-Guarantor Subsidiaries [Member]
Condensed Consolidating Statements of Cash Flows [Line Items]
Net cash provided by (used in) operating activities	1,200	75,100	8,000
Cash flows from investing activities:
Cash paid for acquisitions, net of cash acquired	0	0	0
Capital expenditures	(3,300)	(4,500)	(12,500)
Proceeds from sale of property and equipment	1,800	3,600	3,400
Payments for other investments	(73,300)	(28,200)	(125,600)
Proceeds from other investments	22,600	1,100	69,400
Net cash used in investing activities	(52,200)	(28,000)	(65,300)
Cash flows from financing activities:
Proceeds from credit facilities	24,600	128,000	605,100
Repayments of credit facilities	(28,400)	(130,500)	(587,800)
Repayments of other borrowings and capital lease obligations, net	(9,600)	(18,300)	(16,600)
Payments of acquisition-related contingent consideration	0	(3,200)	(10,200)
Payments to non-controlling interests, including acquisition of interests and distributions	0
(Payments for) proceeds from stock-based awards, net	0	0	0
Repurchase of common stock	0		0
Other financing activities, net	0	0	0
Net financing activities and advances from (to) consolidated affiliates	84,900	(12,100)	60,300
Net cash provided by (used in) financing activities	71,500	(36,100)	50,800
Effect of currency translation on cash	(100)	(1,300)	1,100
Net increase (decrease) in cash and cash equivalents	20,400	9,700	(5,400)
Cash and cash equivalents - beginning of period	9,900	200	5,600
Cash and cash equivalents - end of period	30,300	9,900	200
Eliminations [Member]
Condensed Consolidating Statements of Cash Flows [Line Items]
Net cash provided by (used in) operating activities	0	0	0
Cash flows from investing activities:
Cash paid for acquisitions, net of cash acquired	0	0	0
Capital expenditures	0	0	0
Proceeds from sale of property and equipment	0	0	0
Payments for other investments	0	0	0
Proceeds from other investments	0	0	0
Net cash used in investing activities	0	0	0
Cash flows from financing activities:
Proceeds from credit facilities	0	0	0
Repayments of credit facilities	0	0	0
Repayments of other borrowings and capital lease obligations, net	0	0	0
Payments of acquisition-related contingent consideration	0	0	0
Payments to non-controlling interests, including acquisition of interests and distributions	0
(Payments for) proceeds from stock-based awards, net	0	0	0
Repurchase of common stock	0		0
Other financing activities, net	0	0	0
Net financing activities and advances from (to) consolidated affiliates	0	0	0
Net cash provided by (used in) financing activities	0	0	0
Effect of currency translation on cash	0	0	0
Net increase (decrease) in cash and cash equivalents	0	0	0
Cash and cash equivalents - beginning of period	0	0	0
Cash and cash equivalents - end of period	$ 0	$ 0	$ 0

Schedule II - Valuation and Qualifying Accounts (Details) - USD ($)
$ in Millions

12 Months Ended

Dec. 31, 2017

Dec. 31, 2016

Dec. 31, 2015

$ 42.8

$ 28.0

$ 33.0

50.2

24.6

2.2

0.0

1.0

10.3

(9.4)

(10.8)

(17.5)

Allowance for Doubtful Accounts [Member]

83.6

42.8

28.0

Valuation and Qualifying Accounts [Roll Forward]

8.4

7.7

13.9

^[1]

2.6

2.9

2.1

0.0

^[2]

(2.8)

(2.2)

(8.3)

Costs and Earnings in Excess of Billings Allowance [Member]

8.2

8.4

7.7

Valuation and Qualifying Accounts [Roll Forward]

9.5

6.9

12.5

^[1]

22.3

9.9

0.0

0.0

^[2]

(4.6)

(7.3)

(5.6)

Inventory Valuation Reserve [Member]

27.2

9.5

6.9

Valuation and Qualifying Accounts [Roll Forward]

3.5

2.8

6.4

^[3]

6.2

2.0

0.0

0.0

^[4]

(2.0)

(1.3)

(3.6)

Valuation Allowance for Deferred Tax Assets [Member]

7.7

3.5

2.8

Valuation and Qualifying Accounts [Roll Forward]

21.4

10.6

0.2

^[5]

19.1

9.8

0.1

0.0

1.0

^[6]

10.3

^[6]

0.0