MasTec (MTZ) 10-K 28 Feb 19 2018 FY Annual report Financial data

Document and Entity Information

Document and Entity Information - USD ($) $ in Billions	12 Months Ended
	Dec. 31, 2018	Feb. 25, 2019	Jun. 29, 2018
Document and Entity Information [Abstract]
Document Type	10-K
Amendment Flag	false
Document Period End Date	Dec. 31, 2018
Document Fiscal Year Focus	2,018
Document Fiscal Period Focus	FY
Current Fiscal Year End Date	--12-31
Entity Registrant Name	MASTEC INC
Trading Symbol	MTZ
Entity Central Index Key	15,615
Entity Well-known Seasoned Issuer	Yes
Entity Voluntary Filers	No
Entity Current Reporting Status	Yes
Entity Filer Category	Large Accelerated Filer
Entity Emerging Growth Company	false
Entity Small Business	false
Shell Company	false
Entity Public Float (in dollars)			$ 3.2
Entity Common Stock, Shares Outstanding		76,027,780

Consolidated Statements of Oper

Consolidated Statements of Operations - USD ($) shares in Thousands, $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2018		Dec. 31, 2017		Dec. 31, 2016
Income Statement [Abstract]
Revenue	$ 1,917,600	$ 1,977,200	$ 1,617,800	$ 1,396,800	$ 1,602,900	$ 1,955,800	$ 1,890,200	$ 1,158,200	$ 6,909,417		$ 6,606,978		$ 5,134,703
Costs of revenue, excluding depreciation and amortization	1,654,000	1,681,400	1,366,600	1,237,300	1,421,700	1,726,200	1,626,300	971,100	5,939,308		5,745,307		4,442,125
Depreciation and amortization									212,930		188,049		164,915
Goodwill impairment	47,700								47,662		0		0
General and administrative expenses									287,278		275,103		261,433
Interest expense, net									82,571		61,011		50,734
Equity in earnings of unconsolidated affiliates									(23,855)		(21,328)		(3,528)
Other income, net									(1,780)		(12,990)		(6,795)
Income before income taxes									365,303		371,826		225,819
Provision for income taxes									(106,072)		(22,942)		(91,784)
Net income	31,800	120,500	80,400	26,500	160,700	64,200	83,300	40,600	259,231		348,884		134,035
Net (loss) income attributable to non-controlling interests									(428)		1,671		2,772
Net income attributable to MasTec, Inc.	$ 31,900	$ 120,700	$ 80,500	$ 26,600	$ 160,800	$ 63,800	$ 81,700	$ 41,000	$ 259,659	[1]	$ 347,213	[1]	$ 131,263	[1]
Earnings per share (Note 2):
Basic earnings per share (in dollars per share)	$ 0.42	$ 1.55	$ 1.02	$ 0.33	$ 1.98	$ 0.79	$ 1.01	$ 0.51	$ 3.30		$ 4.29		$ 1.63
Basic weighted average common shares outstanding									78,695		80,903		80,372
Diluted earnings per share (in dollars per share)	$ 0.41	$ 1.52	$ 1.01	$ 0.32	$ 1.95	$ 0.77	$ 0.99	$ 0.50	$ 3.26		$ 4.22		$ 1.61
Diluted weighted average common shares outstanding									79,772		82,325		81,394
[1]	Calculated as total net income less amounts attributable to non-controlling interests.

Consolidated Statements of Comp

Consolidated Statements of Comprehensive Income (Loss) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Statement of Comprehensive Income [Abstract]
Net income	$ 259,231	$ 348,884	$ 134,035
Other comprehensive (loss) income:
Foreign currency translation (losses) gains, net of tax	(2,645)	1,627	2,585
Unrealized gains on equity investee activity, net of tax	5,863	475	3,952
Comprehensive income	262,449	350,986	140,572
Comprehensive (loss) income attributable to non-controlling interests	(428)	1,671	2,772
Comprehensive income attributable to MasTec, Inc.	$ 262,877	$ 349,315	$ 137,800

Consolidated Balance Sheets

Consolidated Balance Sheets - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Current assets:
Cash and cash equivalents	$ 27,422	$ 40,326
Accounts receivable, net (Note 5)	1,923,970	1,598,015
Inventories, net	113,709	76,992
Prepaid expenses	56,558	101,270
Other current assets	47,330	35,763
Total current assets	2,168,989	1,852,366
Property and equipment, net	747,808	706,506
Goodwill, net	1,100,350	1,137,738
Other intangible assets, net	169,370	191,142
Other long-term assets	253,436	178,824
Total assets	4,439,953	4,066,576
Current liabilities:
Current portion of long-term debt	82,655	87,866
Accounts payable	669,712	377,954
Accrued salaries and wages	90,218	89,087
Other accrued expenses	133,033	148,971
Billings in excess of costs and earnings	227,056	194,494
Other current liabilities	80,937	65,455
Total current liabilities	1,283,611	963,827
Long-term debt	1,324,223	1,280,706
Deferred income taxes	263,687	204,518
Other long-term liabilities	176,408	184,172
Total liabilities	3,047,929	2,633,223
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 - 91,327,009 and 90,935,584 (including 1,251,533 and 1,421,041 of unvested stock awards) as of December 31, 2018 and December 31, 2017, respectively	9,133	9,094
Capital surplus	789,009	775,387
Retained earnings	1,118,375	857,154
Accumulated other comprehensive loss	(60,494)	(63,712)
Treasury stock, at cost: 15,329,817 shares and 8,132,811 shares as of December 31, 2018 and 2017, respectively	(466,125)	(147,124)
Total MasTec, Inc. shareholders’ equity	1,389,898	1,430,799
Non-controlling interests	2,126	2,554
Total equity	1,392,024	1,433,353
Total liabilities and equity	$ 4,439,953	$ 4,066,576

Consolidated Balance Sheets (Pa

Consolidated Balance Sheets (Parenthetical) - $ / shares	Dec. 31, 2018	Dec. 31, 2017
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	91,327,009	90,935,584
Treasury stock, shares	15,329,817	8,132,811
Common Stock [Member]
Common stock, shares issued	91,327,009	90,935,584
Restricted Stock Awards [Member] | Common Stock [Member]
Unvested stock awards (in shares)	1,251,533	1,421,041

Consolidated Statements of Equi

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, 2015		88,197,474
Beginning balance at Dec. 31, 2015	$ 943,391	$ 8,820	$ (145,573)	$ 769,996	$ 378,678	$ (72,351)	$ 939,570	$ 3,821
Beginning 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
Acquisition of treasury stock, at cost (in shares)			0
Other activity, net	510						0	510
Ending balance, common shares outstanding (in shares) at Dec. 31, 2016		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)
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 Equity
Cumulative effect of adoption, revenue recognition (Topic 606)	$ 1,562				1,562		1,562
Net income (loss)	259,231				259,659		259,659	(428)
Other comprehensive income (loss)	3,218					3,218	3,218
Non-cash stock-based compensation	13,527			13,527			13,527
Issuance of restricted shares (in shares)		385,392
Issuance of restricted shares	0	$ 39		(39)			0
Other stock issuances, net of shares withheld for taxes (in shares)		6,033
Other stock issuances, net of shares withheld for taxes	134	$ 0		134			134
Acquisition of treasury stock, at cost (in shares)			(7,197,006)
Acquisition of treasury stock, at cost	$ (319,001)		$ (319,001)				(319,001)
Ending balance, common shares outstanding (in shares) at Dec. 31, 2018	91,327,009	91,327,009
Ending balance at Dec. 31, 2018	$ 1,392,024	$ 9,133	$ (466,125)	$ 789,009	$ 1,118,375	$ (60,494)	$ 1,389,898	$ 2,126
Ending balance, treasury shares (in shares) at Dec. 31, 2018	(15,329,817)		(15,329,817)

Consolidated Statements of Cash

Consolidated Statements of Cash Flows - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Cash flows from operating activities:
Net income	$ 259,231	$ 348,884	$ 134,035
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization	212,930	188,049	164,915
Goodwill impairment	47,662	0	0
Non-cash interest expense, net	2,584	3,100	2,994
Non-cash stock-based compensation expense	13,527	15,656	15,072
Provision for (benefit from) deferred income taxes	56,209	18,277	(3,935)
Equity in earnings of unconsolidated affiliates	(23,855)	(21,328)	(3,528)
(Gains) losses on sales of assets, net, including fixed assets held-for-sale	(16,052)	(5,935)	1,957
Other non-cash items, net	8,910	7,222	4,700
Changes in assets and liabilities, net of acquisitions:
Accounts receivable, net	(335,201)	(417,491)	(246,419)
Inventories	(29,366)	36,187	(22,232)
Other assets, current and long-term portion	28,709	(117,091)	44,650
Accounts payable and accrued expenses	251,735	43,883	70,147
Billings in excess of costs and earnings	28,411	46,075	12,131
Other liabilities, current and long-term portion	24,522	(1,392)	31,106
Net cash provided by operating activities	529,956	144,096	205,593
Cash flows from investing activities:
Cash paid for acquisitions, net of cash acquired	(6,684)	(115,995)	(4,102)
Capital expenditures	(180,420)	(123,412)	(117,114)
Proceeds from sale of property and equipment	39,359	19,963	11,239
Payments for other investments	(39,469)	(77,105)	(32,169)
Proceeds from other investments	5,415	23,801	1,125
Net cash used in investing activities	(181,799)	(272,748)	(141,021)
Cash flows from financing activities:
Proceeds from credit facilities	3,418,232	2,699,047	1,681,424
Repayments of credit facilities	(3,359,521)	(2,457,293)	(1,627,129)
Repayments of other borrowings, net	(17,427)	(3,350)	(10,694)
Payments of capital lease obligations	(72,167)	(67,740)	(57,980)
Payments of acquisition-related contingent consideration	(15,929)	(6,676)	(19,822)
Payments to non-controlling interests, including acquisition of interests and distributions	(559)	(22,728)	0
Proceeds from (payments for) stock-based awards, net	226	(3,085)	4,200
Repurchases of common stock	(313,949)	(1,552)	0
Other financing activities, net	0	(6,301)	515
Net cash (used in) provided by financing activities	(361,094)	130,322	(29,486)
Effect of currency translation on cash	33	(111)	(1,303)
Net (decrease) increase in cash and cash equivalents	(12,904)	1,559	33,783
Cash and cash equivalents - beginning of period	40,326	38,767	4,984
Cash and cash equivalents - end of period	27,422	40,326	38,767
Supplemental cash flow information:
Interest paid	81,230	59,157	47,698
Income tax (refunds) payments, net	(21,450)	78,653	59,342
Supplemental disclosure of non-cash information:
Additions to acquisition-related contingent consideration	6,461	102,534	0
Equipment acquired under capital lease and financing arrangements	75,545	150,055	25,092
Accrued capital expenditures	$ 3,987	$ 4,716	$ 1,582

Business, Basis of Presentation

Business, Basis of Presentation and Significant Accounting Policies	12 Months Ended
	Dec. 31, 2018
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, utility and other infrastructure, such as: wireless, wireline/fiber and customer fulfillment activities; petroleum and natural gas pipeline infrastructure; electrical utility transmission and distribution; power generation, including renewables; 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 either the equity method of accounting or under the fair value option. 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. When necessary, certain prior year amounts have been reclassified to conform with the current period presentation. 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 included 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 cost-to-cost method, for which the recorded amounts require estimates of costs to complete and the amount of variable consideration included in the contract transaction price; allowances for doubtful accounts; fair value estimates, including those related to 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 The Company adopted the requirements of Accounting Standards Update (“ASU”) 2014-09, Revenue from Contracts with Customers , which is also referred to as Accounting Standards Codification (“ASC”) Topic 606 (“Topic 606”), under the modified retrospective transition approach effective January 1, 2018, with application to all existing contracts that were not substantially completed as of January 1, 2018. The difference between the recognition criteria under Topic 606 and the Company’s previous revenue recognition practices under the previous revenue recognition guidance, ASC Topic 605-35, was recognized through a cumulative effect adjustment of approximately $2 million that was made to the opening balance of retained earnings as of January 1, 2018. Consistent with the modified retrospective transition approach, the comparative 2017 prior period was not adjusted to conform to the current period presentation. Under Topic 606, revenue is recognized when, or as, control of promised goods and services is transferred to customers, and the amount of revenue recognized reflects the consideration to which an entity expects to be entitled in exchange for the goods and services transferred. The adoption of Topic 606 did not have a material effect on the timing or amount of revenue recognized as compared with the Company’s previous revenue recognition practices. Revenue is primarily recognized by the Company over time utilizing the cost-to-cost measure of progress, which is an input method, on contracts for specific projects, and for certain master service and other service agreements, consistent with the Company’s previous revenue recognition practices. Under Topic 606, the cost-to-cost measure of progress best depicts the continuous transfer of control of goods or services to the customer, and correspondingly, when performance obligations are satisfied, for these contracts. Contracts. The Company derives revenue primarily from construction projects performed under: (i) master and other service agreements, which provide a menu of available services in a specific geographic territory that are utilized on an as-needed basis, and are typically priced using time and materials or a fixed price per unit basis; or (ii) contracts for specific projects requiring the construction and installation of an entire infrastructure system or specified units within an infrastructure system, which are subject to multiple pricing options, including fixed price, unit price, time and materials, or cost plus a markup. Revenue derived from projects performed under master service and other service agreements totaled 35% , 36% and 43% of consolidated revenue for the years ended December 31, 2018 , 2017 and 2016 , respectively. Fixed price contracts provide for a fixed amount of revenue for the entire project. Revenue from these contracts, as well as for certain projects pursuant to master and other service agreements, is recognized over time using the cost-to-cost measure of progress. For these contracts, the cost-to-cost measure of progress best depicts the continuous transfer of control of goods or services to the customer. Such contracts provide that the customer accept completion of progress to date and compensate the Company for services rendered. For certain master service and other service agreements under which the Company performs installation and maintenance services, primarily for install-to-the-home service providers in its Communications segment, revenue is recognized at a point in time. This is generally when the work order has been fulfilled, which is typically the same day the work is initiated. Point in time revenue accounted for approximately 7% of consolidated revenue for the year ended December 31, 2018 . Substantially all of the Company’s other revenue is recognized over time. Contract costs include all direct materials, labor and subcontracted costs, as well as indirect costs related to contract performance, such as indirect labor, supplies, tools, repairs and the operational costs of capital equipment. The cost estimation process for recognizing revenue over time under the cost-to-cost method is based on the professional knowledge and experience of the Company’s project managers, engineers and financial professionals. Management reviews estimates of total contract transaction price and total project costs on an ongoing basis. Changes in job performance, job conditions and management’s assessment of expected variable consideration are factors that influence estimates of the total contract transaction price, total costs to complete those contracts and the Company’s profit recognition. Changes in these factors could result in revisions to revenue in the period in which the revisions are determined, which could materially affect the Company’s consolidated results of operations for that period. Provisions for losses on uncompleted contracts are recorded in the period in which such losses are determined. For both the years ended December 31, 2018 and 2017 , 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, 2017 and 2016 . Revenue recognized for the year ended December 31, 2018 as a result of changes in revenue estimates, including from variable consideration, from performance obligations satisfied, or partially satisfied, in prior periods totaled approximately $38.5 million . The Company may incur certain costs that can be capitalized, such as initial set-up or mobilization costs. Such costs, which are amortized over the life of the respective project, were not material for the year ended December 31, 2018 . The timing of customer billings is generally dependent upon advance billing terms, milestone billings based on completion of certain phases of work, or when services are provided. Under the typical payment terms of master and other service agreements and fixed price contracts, the customer makes progress payments based on quantifiable measures of performance by the Company as defined by each specific agreement. Progress payments, generally net of amounts retained, are paid by the customer over the duration of the contract. For install-to-the-home contracts, work orders are billed and paid as completed. Amounts billed and due from customers, as well as the amount of contract assets, are classified within accounts receivable, net, in the consolidated balance sheets. See Note 5 - Accounts Receivable, Net of Allowance, and Contract Assets and Liabilities for related discussion. Amounts expected to be collected beyond one year are classified as other long-term assets. Performance Obligations. A performance obligation is a contractual promise to transfer a distinct good or service to a customer, and is the unit of account under Topic 606. The transaction price of a contract is allocated to each distinct performance obligation and recognized as revenue when or as the performance obligation is satisfied. The Company’s contracts often require significant services to integrate complex activities and equipment into a single deliverable, and are therefore generally accounted for as a single performance obligation, even when delivering multiple distinct services. Contract amendments and change orders, which are generally not distinct from the existing contract, are typically accounted for as a modification of the existing contract and performance obligation. The vast majority of the Company’s performance obligations are completed within one year . When more than one contract is entered into with a customer on or close to the same date, the Company evaluates whether those contracts should be combined and accounted for as a single contract, as well as whether those contracts should be accounted for as one, or more than one, performance obligation. This evaluation requires significant judgment and is based on the facts and circumstances of the various contracts. Remaining performance obligations represent the amount of unearned transaction price under contracts for which work is wholly or partially unperformed, including the Company’s share of unearned transaction price from its proportionately consolidated non-controlled joint ventures. As of December 31, 2018 , the amount of the Company’s remaining performance obligations was $5.0 billion . The Company expects to recognize approximately $4.3 billion of its remaining performance obligations as revenue during 2019 , with the remainder to be recognized primarily in 2020 . Variable Consideration. Transaction prices for the Company’s contracts may include variable consideration, which comprises items such as change orders, claims and incentives. Management estimates variable consideration for a performance obligation utilizing estimation methods that it believes best predict the amount of consideration to which the Company will be entitled. Variable consideration is included in the estimated transaction price if it is probable that when the uncertainty associated with the variable consideration is resolved, there will not be a significant reversal of the cumulative amount of revenue that has been recognized. Management’s estimates of variable consideration and the determination of whether to include estimated amounts in the transaction price are based largely on engineering studies and legal opinions, past practices with the customer, specific discussions, correspondence or preliminary negotiations with the customer and all other relevant information that is reasonably available at the time of the estimate. The effect of variable consideration on the transaction price of a performance obligation is typically recognized as an adjustment to revenue on a cumulative catch-up basis, as such variable consideration, which typically pertains to changed conditions and scope, is generally for services encompassed under the existing contract. To the extent unapproved change orders, claims and other variable consideration reflected in transaction prices are not resolved in the Company’s favor, or to the extent incentives reflected in transaction prices are not earned, there could be reductions in, or reversals of, previously recognized revenue. As of December 31, 2018 and 2017 , the Company included approximately $56 million and $146 million , respectively, of change orders and/or claims in the transaction price for certain contracts that were in the process of being resolved in the normal course of business, including through negotiation, arbitration and other proceedings. These transaction price adjustments are included within costs and earnings in excess of billings or accounts receivable, net of allowance, as appropriate. As of both December 31, 2018 and 2017 , these change orders and/or claims were primarily related to certain pipeline construction projects in the Oil and Gas segment. The Company actively engages with its customers to complete the final approval process, and generally expects these processes to be completed within one year . Amounts ultimately realized upon final acceptance by customers could be higher or lower than such estimated amounts. 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 anticipated losses on its accounts receivable balances either when a business unit has historical experience of losses that are considered to be ordinary course, and/or for specific receivables, when it is probable that the 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. 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 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. The value of inventory may also decrease due to obsolescence, physical deterioration, damage, changes in price levels, or other causes. Inventory valuation allowances are determined based upon specific facts and circumstances and market conditions. As of December 31, 2018 and 2017 , valuation allowances for inventory totaled $7.8 million and $7.7 million , respectively. Cash and Cash Equivalents Cash consisting of interest-bearing demand deposits is carried at cost, which approximates fair value. Highly liquid investments purchased with an original maturity of three months or less 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, 2018 and 2017 are amounts held by entities that are proportionately consolidated totaling $11.8 million and $17.3 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. 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 the amount 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, and outstanding balances on its credit facilities approximate their fair values. 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’s investment arrangements include equity interests in various business entities and participation in contractual joint ventures, some of which may involve the extension of loans or other types of financing arrangements. 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, 2018 , the Company determined that certain of its investment arrangements were VIEs. The Company does not, however, have the power to direct the primary activities that most significantly impact the economic performance of these VIEs and the Company is not the primary beneficiary; accordingly, it has not consolidated these VIEs. The Company’s investments in entities for which the Company does not have a controlling interest and for which it is not the primary beneficiary, but for which it has the ability to exert significant influence, are accounted for using either the equity method of accounting or under the fair value option. 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. Distributions received from equity method investees are reflected in the statements of cash flows using the nature of distributions approach, under which distributions are classified based on the nature of the activity that generated them. 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 Company adopted ASU 2016-01, Financial Instruments - Overall (Subtopic 825-10): Recognition and Measurement of Financial Assets and Financial Liabilities and its related clarifying ASUs (“ASU 2016-01”) as of January 1, 2018. ASU 2016-01 provided guidance for the recognition, measurement, presentation and disclosure of financial assets and financial liabilities, including equity investments other than those accounted for under the equity method of accounting or those that are consolidated . Under the new guidance, which was applicable to the Company on a prospective basis, e quity investments, other than those accounted for as equity method investments or those that are proportionately consolidated, are measured at fair value if their fair values are readily determinable. Equity investments that do not have readily determinable fair values are measured at cost, adjusted for changes from observable market transactions, less impairment (“adjusted cost basis”). The Company evaluates its investments for impairment by considering a variety of factors, including the earnings capacity of the related investments. Fair value measurements for the Company’s equity investments are classified within Level 3 of the fair value hierarchy based on the nature of the fair value inputs. Realized and unrealized gains or losses are recognized in other income or expense. The adoption of ASU 2016-01 will result in volatility in other income or expense upon the occurrence of observable price changes related to, or impairments of, the Company’s investments measured on an adjusted cost basis. The other provisions of ASU 2016-01 did not have a material effect on the Company’s consolidated financial statements. For further information pertaining to the Company’s equity investments, see Note 4 - Fair Value of Financial Instruments . 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 that extend the life of the related assets 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. 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 revenue and operating costs for the business as well as anticipated future economic conditions. 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, 2018 , there were no material impairments of 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, monitors these assets for potential indicators of impairment. 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. If two or more components are deemed economically similar, those components are aggregated into one reporting unit when performing the annual goodwill impairment test. Based on management’s review of its components and their related operations, the Company combines all of the components of its Electrical Transmission operating segment into one reporting unit and beginning in 2017, combines two of the components within its Power Generation and Industrial operating segment into one reporting unit. These components were deemed to be economically similar and share operational, sales and general and administrative resources. All of the Company’s other components each comprise one reporting unit. The Company adopted ASU 2017-04, Intangibles - Goodwill and Other (Topic 350): Simplifying the Test for Goodwill Impairment (“ASU 2017-04”) as of January 1, 2018. ASU 2017-04 eliminated the second step in goodwill impairment testing, which required that goodwill impairment losses be measured as the difference between the implied value of a reporting unit’s goodwill and its carrying amount. Under the new guidance, goodwill impairment losses are measured as the excess of a reporting unit’s carrying amount, including goodwill and related goodwill tax effects, over its fair value. For each of the three years in the period ended December 31, 2018 , 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 mark

Earnings Per Share

Earnings Per Share	12 Months Ended
	Dec. 31, 2018
Earnings Per Share [Abstract]
Earnings Per Share	Note 2 – Earnings Per Share Basic earnings or loss per share is computed by dividing net income 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 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. For each of the three years ended December 31, 2018 , 2017 and 2016 , anti-dilutive common stock equivalents as calculated under the treasury stock method were de minimis. 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, 2018 2017 2016 Net income attributable to MasTec: Net income - basic and diluted (a) $ 259,659 $ 347,213 $ 131,263 Weighted average shares outstanding: Weighted average shares outstanding - basic 78,695 80,903 80,372 Dilutive common stock equivalents 1,077 1,422 1,022 Weighted average shares outstanding - diluted 79,772 82,325 81,394 (a) Calculated as total net income less amounts attributable to non-controlling interests. The Company repurchased approximately 7.2 million shares of its common stock during the year ended December 31, 2018 , as discussed in Note 11 - Equity . The effect of these repurchases on the Company’s weighted average shares outstanding for the year ended December 31, 2018 was a reduction of 2.8 million shares due to the timing of the repurchases, which occurred throughout the year. In future periods, our weighted average shares outstanding will be reduced by an additional 4.4 million shares due to the full effect of these share repurchases.

Goodwill and Other Intangible A

Goodwill and Other Intangible Assets	12 Months Ended
	Dec. 31, 2018
Goodwill and Intangible Assets Disclosure [Abstract]
Goodwill and Other Intangible Assets	Note 3 – Goodwill and Other Intangible Assets During the fourth quarter of 2018, the Company recorded a pre-tax non-cash goodwill impairment charge of $47.7 million for its Canadian oil and gas reporting unit. This reporting unit’s current operating performance, as well as its future operating and cash flow expectations, have been negatively affected by current market conditions. See Note 1 - Business, Basis of Presentation and Significant Accounting Policies for additional discussion. 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, 2016 $ 420.7 $ 377.6 $ 149.9 $ 117.6 $ 1,065.8 Accumulated impairment loss (a) — (69.9 ) — — (69.9 ) 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 Additions from new business combinations — — — 9.8 9.8 Measurement period adjustments, net (b) 1.4 5.7 — (2.5 ) 4.6 Goodwill impairment — (47.7 ) — — (47.7 ) Currency translation adjustments — (4.0 ) — — (4.0 ) Goodwill, net, as of December 31, 2018 $ 467.8 $ 339.6 $ 149.9 $ 143.1 $ 1,100.4 Accumulated impairment loss (a) — (116.0 ) — — (116.0 ) Goodwill, gross, as of December 31, 2018 $ 467.8 $ 455.6 $ 149.9 $ 143.1 $ 1,216.4 (a) Accumulated impairment losses include the effects of currency translation gains and/or losses. (b) Represents adjustments to preliminary estimates of fair value within the measurement period of up to one year from the date of acquisition. The following table provides a reconciliation of changes in other intangible assets, net, 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, 2016 $ 34.5 $ 74.6 $ 195.1 $ 19.1 $ 323.3 Accumulated amortization (131.9 ) (11.7 ) (143.6 ) 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 Additions from new business combinations — — 3.3 0.3 3.6 Measurement period adjustments (b) — — — (0.7 ) (0.7 ) Amortization expense (19.2 ) (1.4 ) (20.6 ) Currency translation adjustments — (3.6 ) (0.3 ) (0.1 ) (4.0 ) Other intangible assets, net, as of December 31, 2018 $ 34.5 $ 74.0 $ 54.4 $ 6.5 $ 169.4 Remaining weighted average amortization period (in years) 8 7 8 (a) Consists principally of trade names and non-compete agreements. (b) Represents adjustments to preliminary estimates of fair value within the measurement period of up to one year from the date of acquisition. Amortization expense associated with intangible assets for the years ended December 31, 2018 , 2017 and 2016 totaled $20.6 million , $20.9 million and $21.3 million , respectively. Expected future amortization expense as of December 31, 2018 is summarized in the following table (in millions): Amortization Expense 2019 $ 14.6 2020 11.2 2021 8.5 2022 6.9 2023 4.9 Thereafter 14.8 Total $ 60.9 2018 Acquisitions. During the first quarter of 2018, MasTec acquired all of the equity interests in a construction management firm specializing in steel building systems and acquired a wind turbine services company, both of which are included in the Company’s Power Generation and Industrial segment. The aggregate purchase price for these entities was composed of approximately $6.8 million in cash and estimated earn-out liabilities, net, totaling $1.5 million as of December 31, 2018 . Determination of the estimated fair values of the net assets acquired and the estimated earn-out liabilities for these acquisitions was preliminary as of December 31, 2018 ; as a result, further adjustments to these estimates may occur. As of December 31, 2018 , the range of remaining potential undiscounted earn-out liabilities, net, for the 2018 acquisitions was estimated to be up to $7 million ; however, there is no maximum payment amount . 2017 Acquisitions. During 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. The following table summarizes the fair values of consideration paid and net assets acquired as of the respective dates of acquisition, as adjusted (in millions): Acquisition consideration: 2017 Cash $ 120.4 Estimated fair value of contingent consideration (earn-out liability) 98.5 Total consideration transferred $ 218.9 Identifiable assets acquired and liabilities assumed: Current assets, primarily composed of accounts receivable and $2.8 million of cash acquired $ 43.8 Property and equipment and other long-term assets 57.2 Amortizing intangible assets 28.1 Current liabilities, including current portion of capital lease obligations and long-term debt (29.5 ) Long-term debt, including capital lease obligations (9.9 ) Deferred income taxes and other long-term liabilities (12.0 ) Total identifiable net assets $ 77.7 Goodwill $ 141.2 Total net assets acquired, including goodwill $ 218.9 Amortizing intangible assets related to the 2017 acquisitions are primarily composed of customer relationships, backlog and certain other intangible assets, which had weighted average lives, as adjusted, of approximately 11 years, 4 years and 6 years, respectively, and a weighted average life of 10 years in total. Amortizing intangible assets are 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’s industry-specific project management expertise, as well as synergies expected to be achieved from the combined operations of the acquired companies and MasTec. Approximately $94 million of the goodwill balance related to the 2017 acquisitions is expected to be tax deductible as of December 31, 2018 . The contingent consideration (earn-out liability) included in the table above equals a portion of the acquired companies’ earnings before interest, taxes, depreciation and amortization (“EBITDA”) in excess of thresholds agreed upon with the sellers, if applicable. Earn-outs are generally payable annually for a period of five years, as set forth in the respective purchase agreements. 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 significantly higher or lower potential earn-out liabilities. As of December 31, 2018 , the range of remaining potential undiscounted earn-out liabilities for the 2017 acquisitions was estimated to be between $24 million and $145 million ; however, there is no maximum payment amount . Pro Forma Financial Information and Acquisition Results. For the years ended December 31, 2018 and 2017 , unaudited supplemental pro forma revenue totaled approximately $6,912.5 million and $6,724.8 million , respectively, and unaudited supplemental pro forma net income totaled approximately $257.7 million and $351.3 million , respectively. These unaudited pro forma financial results represent the results of operations of the companies acquired as if the acquired companies had been consolidated as of the beginning of the year prior to their acquisition, and are provided for illustrative purposes only. These unaudited pro forma financial results 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 Company’s unaudited pro forma financial results were prepared by adjusting the historical results of MasTec to include the unaudited historical results of the acquired businesses described above, and then adjusted for (i) acquisition costs; (ii) amortization expense resulting from the acquired intangible assets; (iii) interest expense as a result of the cash consideration paid; (iv) interest expense from debt repaid upon acquisition; and (iv) elimination of the effects of intercompany transactions and other purchase accounting related adjustments. These unaudited 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 the Company’s control. For the years ended December 31, 2018 and 2017, the Company’s consolidated results of operations included acquisition-related revenue of approximately $154.4 million and $160.1 million , respectively, and acquisition-related net income of approximately $1.4 million and $10.2 million , respectively, based on the Company’s consolidated effective tax rates, including, for 2018, the effects 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 Instrum

Fair Value of Financial Instruments	12 Months Ended
	Dec. 31, 2018
Fair Value Disclosures [Abstract]
Fair Value of Financial Instruments	Note 4 – Fair Value of Financial Instruments Acquisition-Related Contingent Consideration Acquisition-related contingent consideration, or “earn-outs,” represent the estimated fair value of future amounts payable for acquisitions of businesses and other interests. Acquisition-related contingent consideration is based on management estimates and entity-specific assumptions, which are Level 3 inputs, and is evaluated on an ongoing basis. As of December 31, 2018 and 2017 , the estimated fair value of the Company’s earn-out liabilities totaled $118.1 million and $117.2 million , respectively, of which $29.6 million and $22.6 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, which incorporate 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 significantly higher or lower potential earn-out liabilities. As of December 31, 2018 , the range of potential undiscounted earn-out liabilities was estimated to be between $30 million and $157 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; changes in the expected fair value of future earn-out obligations; and payments. Fair value adjustments for earn-out liabilities that relate to new information obtained about the facts and circumstances that existed as of the date of acquisition for a period of up to one year, which are referred to as measurement period adjustments, are recorded to goodwill. Other revisions to the expected fair value of future earn-out liabilities are reflected as income or expense, as appropriate. Payments of acquisition-related contingent consideration, to the extent they relate to estimated liabilities as of the date of acquisition, are reflected within financing activities in the consolidated statements of cash flows, whereas payments in excess of acquisition date liabilities are classified within operating activities. For the years ended December 31, 2018 and 2017 , additions to acquisition-related contingent consideration from new business combinations totaled approximately $1.5 million and $102.5 million , respectively. There were no additions from new business combinations for the year ended December 31, 2016 . Measurement period adjustments related to acquisition-related contingent consideration totaled a net increase of approximately $5.0 million for the year ended December 31, 2018 and related primarily to a business in the Company’s Oil and Gas segment. Fair value adjustments related to acquisition-related contingent consideration, including those related to finalization of completed earn-out arrangements, totaled a net increase of approximately $17.5 million for the year ended December 31, 2018 , primarily for businesses in the Company’s Oil and Gas and Communications segments and for the year ended December 31, 2017 , totaled a decrease of $12.3 million for businesses in the Company’s Communications and Electrical Transmission segments. For the year ended December 31, 2016 , fair value adjustments, including those related to finalization of completed earn-out arrangements, totaled a net increase of approximately $2.7 million for businesses in the Company’s Oil and Gas and Communications segments. Payments of acquisition-related contingent consideration, including payments in excess of acquisition date liabilities, totaled approximately $23.1 million , $18.8 million and $15.8 million for the years ended December 31, 2018 , 2017 and 2016 , respectively. Equity Investments The Company’s equity investments as of December 31, 2018 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”), which are accounted for as equity method investments; (ii) a $15 million investment in Cross Country Infrastructure Services, Inc. (“CCI”); (iii) the Company’s interests in certain proportionately consolidated non-controlled contractual joint ventures; (iv) the Company’s equity interests in Pensare Acquisition Corp. (“Pensare”); and (v) certain other equity investments. See Note 15 - Related Party Transactions for additional information related to certain of the Company’s equity investments. As of December 31, 2018 and 2017 , the aggregate carrying value of the Company’s equity investments totaled approximately $197 million and $141 million , respectively, including approximately $18 million of equity investments measured on an adjusted cost basis as of December 31, 2018 , and measured at cost as of December 31, 2017 . There were no impairments of, or material changes in the fair value of, these investments during either of the years then ended. 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, for which operations commenced in 2017. For the years ended December 31, 2018 , 2017 and 2016 , the Company made equity and other contributions to these joint ventures of approximately $28 million , $73 million and $27 million , respectively. The Company previously issued letters of credit in connection with its equity commitments in the Waha JVs. As of December 31, 2018 , there were no letters of credit remaining, and as of December 31, 2017 , $19 million in letters of credit were outstanding. 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 $23.9 million and $21.3 million , for the years ended December 31, 2018 and 2017 , respectively, and for the year ended December 31, 2016 , was de minimis. Cumulative undistributed earnings from the Waha JVs, which represents cumulative equity in earnings for the Waha JVs, less distributions of earnings, totaled $29.9 million as of December 31, 2018 . For the year ended December 31, 2018 , the Company received $10.9 million in distributions of earnings from the Waha JVs, which is included within operating cash flows. The Company’s net investment in the Waha JVs, which differs from its proportionate share of the net assets of the Waha JVs, due primarily to capitalized investment costs, totaled approximately $168 million and $121 million as of December 31, 2018 and 2017 , respectively. In the past, certain subsidiaries of MasTec have provided pipeline construction services to the Waha JVs. Revenue and related receivables were de minimis as of and for the year ended December 31, 2018 . Revenue recognized in connection with work performed for the Waha JVs, including intercompany eliminations, totaled $256.1 million and $245.0 million for the years ended December 31, 2017 and 2016 , respectively, and as of December 31, 2017 , related receivables, net of billings in excess of costs and earnings, totaled $2.8 million . The Waha JVs are party to separate non-recourse financing facilities, each of which are secured by pledges of the equity interests in the respective entities, as well as a first lien security interest over virtually all of their assets. The Waha JVs are also party to certain interest rate swaps, which are 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, 2018 , 2017 and 2016 , the Company’s proportionate share of unrecognized unrealized activity on these interest rate swaps were gains of approximately $7.7 million , $0.8 million and $6.4 million , respectively, or $5.9 million , $0.5 million and $4.0 million , respectively, net of tax. 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. José R. Mas, MasTec’s Chief Executive Officer, is a director of Pensare. 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 are exercisable at a purchase price of $11.50 per share after Pensare successfully completes a business combination transaction. Both the warrants and the shares contained an expiration and/or forfeiture clause without the successful completion of a business combination transaction, for which the required completion date was extended in January 2019 from February 1, 2019 to May 1, 2019. On January 31, 2019, Pensare entered into a business combination agreement with U.S TelePacific Holdings Corp. (“TPx”), the completion of which is pending shareholder approval. TPx is a provider of unified communications and cloud-focused managed information technology services. The shares, which are measured on an adjusted cost basis, and the warrants, which are derivative financial instruments, are included within other long-term assets in the Company’s consolidated financial statements as of December 31, 2018 . Due to the nature of the restrictions, the fair value of the shares is not readily determinable. The fair value of the warrants is determined based on observable and unobservable inputs, including market volatility and the rights and obligations of the warrants, which are Level 3 inputs. For the years ended December 31, 2018 and 2017 , there were no material changes in the fair value of the Company’s investment in Pensare. During the second quarter of 2018, the Company invested $10.0 million for an equity interest of approximately 40% in LifeShield, LLC (“LifeShield”), a home security company, which was measured under the fair value option as this valuation approach was considered to provide an accurate reflection of the economic performance of LifeShield and the value of the Company’s equity interest in the business. To determine the fair value of this investment under the fair value option, the Company estimated the fair value of LifeShield using Level 3 inputs, considering both an income approach, based on discounted cash flows, and a market approach, based on market multiples, and then estimated the fair value of the Company’s investment using an option pricing model. As of December 31, 2018 , the fair value of this investment was determined to approximate its purchase price. In February 2019, the Company sold its equity interest in LifeShield for approximately $11 million , subject to customary escrow arrangements. In connection with the 2014 acquisition of Pacer Construction Holdings Corporation and its affiliated operating companies (collectively, “Pacer”), the Company acquired an investment, for which the Company now has minimal involvement, that is in the final stages of being liquidated and is being managed by a receiver. The Company regularly reviews this investment for potential changes in expected recovery estimates, and during years ended December 31, 2018 , 2017 and 2016 , recorded $0.9 million of expense, $0.4 million of expense and $3.6 million of income, respectively, related to changes in expected recovery estimates. The Company received $5.4 million and $22.5 million of proceeds from the receiver during the years ended December 31, 2018 and 2017 , respectively. The net carrying value of this asset, which is included within other current assets, totaled $2.9 million and $9.6 million as of December 31, 2018 and 2017 , respectively. In 2016 , Pacer performed construction services on behalf of entities in which it had an equity interest and recognized revenue totaling $0.6 million for the year then ended. Summarized Financial Information of Equity Method Investments The following presents summarized information for the Company’s significant equity method investments (in millions): December 31, 2018 2017 Current assets $ 137.3 $ 136.8 Long-term assets 1,352.1 1,306.3 Total assets $ 1,489.4 $ 1,443.1 Current liabilities $ 31.3 $ 121.2 Long-term liabilities 966.1 976.5 Total liabilities $ 997.4 $ 1,097.7 For the Years Ended December 31, 2018 2017 2016 Revenue $ 145.8 $ 114.5 $ — Net income (loss) $ 72.4 $ 64.5 $ (0.2 ) Senior Notes As of both December 31, 2018 and 2017 , the gross carrying amount of the Company’s 4.875% Senior Notes, which are measured at fair value on a non-recurring basis, totaled $400 million . As of December 31, 2018 and 2017 , the estimated fair value of the 4.875% Senior Notes, based on Level 1 inputs, totaled $392.0 million and $410.0 million , respectively.

Accounts Receivable, Net of All

Accounts Receivable, Net of Allowance, and Contract Assets and Liabilities	12 Months Ended
	Dec. 31, 2018
Receivables [Abstract]
Accounts Receivable, Net of Allowance, and Contract Assets and Liabilities	Note 5 – Accounts Receivable, Net of Allowance, and Contract Assets and Liabilities The following table provides details of accounts receivable, net of allowance, and contract assets (together, “accounts receivable, net”) as of the dates indicated (in millions): December 31, 2018 2017 Contract billings $ 687.6 $ 683.9 Less allowance for doubtful accounts (16.3 ) (8.2 ) Accounts receivable, net of allowance $ 671.3 $ 675.7 Retainage 230.2 323.1 Costs and earnings in excess of billings 1,022.5 599.2 Retainage and costs and earnings in excess of billings (together, "contract assets") $ 1,252.7 $ 922.3 Accounts receivable, net $ 1,924.0 $ 1,598.0 Contract billings represent the amount of performance obligations that have been billed but not yet collected. Contract assets consist of costs and earnings in excess of billings (“CIEB”) and retainage. CIEB, which is also referred to as work in process, represents the estimated value of unbilled work for projects with performance obligations recognized over time. Retainage represents a portion of the contract amount that has been billed, but for which the contract allows the customer to retain a portion of the billed amount until final contract settlement (generally, from 5% to 10% of contract billings). Retainage is not considered to be a significant financing component because the intent is to protect the customer. CIEB and retainage amounts are generally classified as current assets within the Company’s consolidated balance sheets. Retainage that has been billed, but is not due until completion of performance and acceptance by customers, is generally expected to be collected within one year. Accounts receivable expected to be collected beyond one year are recorded within other long-term assets. The increase in the CIEB balance for the year ended December 31, 2018 was driven largely by increased oil and gas pipeline project activity during the fourth quarter of 2018 as compared with 2017 within the Company’s Oil and Gas segment. Under certain contracts, the Company may be entitled to invoice the customer and receive payments in advance of performing the related contract work. In those instances, the Company recognizes a liability for advance billings in excess of revenue recognized, which is referred to as billings in excess of costs and earnings (“BIEC”). BIEC is not considered to be a significant financing component because it is generally used to meet working capital demands that can be higher in the early stages of a contract. Contract liabilities consist primarily of such BIEC, which are generally classified within current liabilities on the Company’s consolidated balance sheets. BIEC totaled approximately $227.1 million and $194.5 million as of December 31, 2018 and 2017 , respectively. For the year ended December 31, 2018 , the Company recognized revenue of approximately $139.8 million related to amounts that were included in BIEC as of December 31, 2017 , resulting primarily from the advancement of physical progress on the respective projects during the period. Contract liabilities also include the amount of any accrued project losses, which are classified within other current liabilities on the Company’s consolidated balance sheets. Total contract liabilities, including accrued project losses, totaled approximately $231.6 million and $206.1 million as of December 31, 2018 and 2017 , respectively. Activity in the allowance for doubtful accounts for the periods indicated is as follows (in millions): For the Years Ended December 31, 2018 2017 Allowance for doubtful accounts at beginning of year $ 8.2 $ 8.4 Provision for doubtful accounts 8.6 2.6 Amounts charged against the allowance (0.5 ) (2.8 ) Allowance for doubtful accounts at end of year $ 16.3 $ 8.2 Impairment losses on contract assets were not material for the year ended December 31, 2018 . 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, interest rates and changes in customer payment terms, improve the collection cycle time of the related receivables. Cash collected from these arrangements 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 $11.1 million , $6.0 million and $2.7 million for the years ended December 31, 2018 , 2017 and 2016 , respectively.

Property and Equipment, Net

Property and Equipment, Net	12 Months Ended
	Dec. 31, 2018
Property, Plant and Equipment [Abstract]
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, 2018 2017 Estimated Useful Lives (in years) Land $ 4.6 $ 4.6 Buildings and leasehold improvements 30.3 26.7 3-40 Machinery and equipment 1,391.8 1,261.9 2-20 Office furniture and equipment 166.7 149.9 3-7 Construction in progress 20.1 12.5 Total property and equipment $ 1,613.5 $ 1,455.6 Less accumulated depreciation and amortization (865.7 ) (749.1 ) Property and equipment, net $ 747.8 $ 706.5 The gross amount of capitalized internal-use software, which is included within office furniture and equipment, totaled $122.0 million and $109.9 million as of December 31, 2018 and 2017 , respectively. Capitalized internal-use software, net of accumulated amortization, totaled $26.5 million and $23.5 million as of December 31, 2018 and 2017 , respectively. Depreciation and amortization expense associated with property and equipment for the years ended December 31, 2018 , 2017 and 2016 totaled $192.3 million , $167.2 million and $143.6 million , respectively.

Debt

Debt	12 Months Ended
	Dec. 31, 2018
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 2018 2017 Senior secured credit facility: February 22, 2022 Revolving loans $ 456.9 $ 377.7 Term loan 376.9 396.9 4.875% Senior Notes March 15, 2023 400.0 400.0 Capital lease obligations, weighted average interest rate of 3.9% In installments through December 31, 2023 183.2 181.2 Other debt obligations — 25.8 Total long-term debt obligations $ 1,417.0 $ 1,381.6 Less unamortized deferred financing costs (10.1 ) (13.0 ) Total debt, net of deferred financing costs $ 1,406.9 $ 1,368.6 Current portion of long-term debt 82.7 87.9 Long-term debt $ 1,324.2 $ 1,280.7 Senior Secured Credit Facility The Company has a senior secured credit facility (the “Credit Facility”). Under the Credit Facility, aggregate borrowing commitments totaled approximately $1.5 billion as of December 31, 2018 , composed of $1.1 billion of revolving commitments and a term loan of approximately $0.4 billion . The term loan is subject to amortization in quarterly principal installments. An initial installment of $3.1 million was paid in December 2017, and quarterly installments of $5.0 million commenced in the first quarter of 2018. Quarterly principal installments on the term loan are subject to adjustment, if applicable, for certain prepayments. The 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 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 differing terms and pricing. 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 Credit Facility, plus a margin of 1.25% to 2.00%, or (b) a Base Rate, as defined in the Credit Facility, plus a margin of 0.25% 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 Credit Facility are subject to a letter of credit fee of 1.25% to 2.00%, and performance standby letters of credit are subject to a letter of credit fee of 0.50% to 1.00%. The Company must also pay a commitment fee to the lenders of 0.20% to 0.40% on any unused availability. 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, 2018 and 2017 , outstanding revolving loans, which included $128 million and $117 million , respectively, of borrowings denominated in foreign currencies, accrued interest at weighted average rates of approximately 4.23% and 3.69% per annum, respectively. The term loan accrued interest at a rate of 4.27% and 3.07% as of December 31, 2018 and 2017 , respectively. Letters of credit of approximately $88.2 million and $157.1 million were issued as of December 31, 2018 and 2017 , respectively. As of December 31, 2018 and 2017 , letters of credit fees accrued at 0.875% and 0.625% per annum, respectively, for performance standby letters of credit, and at 1.75% and 1.50% 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, 2018 and 2017 , availability for revolving loans totaled $554.9 million and $565.2 million , respectively, or up to $554.9 million and $492.9 million , respectively, for new letters of credit. Revolving loan borrowing capacity included $91.9 million and $183.4 million of availability in either Canadian dollars or Mexican pesos as of December 31, 2018 and 2017 , respectively. The unused facility fee as of December 31, 2018 and 2017 accrued at a rate of 0.35% and 0.25% , 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, 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, 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, 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 cash 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: (i) the working capital requirements of its foreign operations, and (ii) certain letter of credit issuances. Borrowings under the Company’s foreign credit facilities, which have varying dates of maturity and are generally renewed on an annual basis, are denominated in Canadian dollars. As of both December 31, 2018 and 2017 , maximum borrowing capacity totaled Canadian $20.0 million , or approximately $14.7 million and $15.9 million , respectively. As of December 31, 2018 , there were no outstanding borrowings, and as of December 31, 2017 , outstanding borrowings totaled approximately $10.4 million and accrued interest at a weighted average rate of 4.0% . 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. Additionally, the Company has a separate credit facility, which is renewable on an annual basis, under which it may issue up to $50.0 million of performance standby letters of credit. As of December 31, 2018 , letters of credit issued under this facility totaled $40.2 million and accrued fees at 0.75% per annum. 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 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. 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, 2018 and 2017 . Contractual Maturities of Debt and Capital Lease Obligations Contractual maturities of MasTec’s debt and capital lease obligations as of December 31, 2018 were as follows (in millions): 2019 $ 83.1 2020 76.2 2021 63.4 2022 792.9 2023 401.4 Thereafter — Total $ 1,417.0 As of both December 31, 2018 and 2017 , accrued interest payable, which is recorded within other accrued expenses in the consolidated balance sheets, totaled $7.4 million .

Lease Obligations

Lease Obligations	12 Months Ended
	Dec. 31, 2018
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, 2018 and 2017 , which are included within property and equipment, net, totaled $337.6 million and $418.0 million , respectively. Assets held under capital leases, net of accumulated depreciation, totaled $246.8 million and $277.3 million as of December 31, 2018 and 2017 , 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 $115.0 million , $104.2 million and $100.5 million for the years ended December 31, 2018 , 2017 and 2016 , respectively. The Company also incurred rent and related expense for facilities, vehicles and equipment having original terms of one year or less totaling approximately $472.1 million , $461.0 million and $298.0 million for the years ended December 31, 2018 , 2017 and 2016 , 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, 2018 , were as follows (in millions): Capital Leases Operating Leases 2019 $ 68.2 $ 86.4 2020 60.2 60.4 2021 46.7 37.1 2022 20.0 21.7 2023 1.5 12.1 Thereafter — 21.8 Total minimum lease payments $ 196.6 $ 239.5 Less amounts representing interest (13.4 ) Total capital lease obligations, net of interest $ 183.2 Less current portion (63.1 ) Long-term portion of capital lease obligations, net of interest $ 120.1 See Note 1 - Business, Basis of Presentation and Significant Accounting Policies for information pertaining to the Company’s January 1, 2019 adoption of ASU 2016-02, Leases (Topic 842) , which, together with its related clarifying ASUs, provided revised guidance for lease accounting and related disclosure requirements.

Stock-Based Compensation and Ot

Stock-Based Compensation and Other Employee Benefit Plans	12 Months Ended
	Dec. 31, 2018
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 participants, 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, 2018 , including ESPPs, there were approximately 4,429,000 shares available for future grant. Non-cash stock-based compensation expense under all plans totaled $13.5 million , $15.7 million and $15.1 million for the years ended December 31, 2018 , 2017 and 2016 , respectively. Income tax benefits associated with stock-based compensation arrangements totaled $4.9 million , $11.2 million and $5.6 million for the years ended December 31, 2018 , 2017 and 2016 , respectively, including net tax benefits related to the vesting of share-based payment awards totaling $1.6 million and $5.4 million for the years ended December 31, 2018 and 2017 , respectively, and a net tax deficiency of $0.1 million for the year ended December 31, 2016 . Restricted Shares MasTec grants restricted stock awards and restricted stock units (together, “restricted shares”) to eligible participants, 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, 2018 was approximately $24.4 million , which is expected to be recognized over a weighted average period of approximately 2.3 years . The intrinsic value of restricted shares that vested, which is based on the market price on the date of vesting, totaled $16.6 million , $39.7 million and $3.5 million for the years ended December 31, 2018 , 2017 and 2016 , respectively. Activity, restricted shares: (a) Restricted Per Share Weighted Average Grant Date Fair Value 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 Granted 423,596 41.41 Vested (554,900 ) 17.73 Canceled/forfeited (47,054 ) 22.26 Non-vested restricted shares, as of December 31, 2018 1,270,233 $ 31.80 (a) Includes 18,700 , 27,550 and 43,300 restricted stock units as of December 31, 2018 , 2017 and 2016 , 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, 2018 2017 2016 Cash proceeds (in millions) $ 4.2 $ 3.3 $ 2.7 Common shares issued 110,506 92,145 144,183 Weighted average price per share $ 37.98 $ 35.92 $ 18.55 Weighted average per share grant date fair value $ 9.36 $ 9.24 $ 5.00 Stock Options The Company previously granted options to purchase its common stock to eligible participants, of which all remaining stock options were exercised in 2016. The intrinsic value of options exercised in 2016 totaled $1.8 million , and related proceeds, net of shares withheld in cashless option exercises, totaled $2.1 million . 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, 2018 , 2017 and 2016 , matching contributions totaled approximately $13.4 million , $11.9 million and $11.1 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 $10.0 million and $9.4 million as of December 31, 2018 and 2017 , respectively. Total deferred compensation plan liabilities, which are included within other long-term liabilities in the consolidated balance sheets, totaled $10.2 million and $9.7 million as of December 31, 2018 and 2017 , respectively.

Other Retirement Plans

Other Retirement Plans	12 Months Ended
	Dec. 31, 2018
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, including certain subsidiaries in Canada, 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 2018 2017 2016 Expiration Date of CBA 2018 As of 2017 As of FIP/RP Status Surcharge Pipeline Industry Pension Fund 736146433 001 $ 20.7 $ 28.8 $ 15.9 05/31/2020 Green 12/31/2017 (a) Green 12/31/2016 (a) NA No Central Pension Fund of the IUOE & Participating Employers 366052390 001 20.4 21.6 19.3 05/31/2020 Green 01/31/2018 Green 01/31/2017 NA No Teamsters National Pipe Line Pension Plan 461102851 001 7.4 7.6 3.6 05/31/2020 Green 12/31/2017 (a) Green 12/31/2016 (a) NA No International Union of Operating Engineers Local 132 Pension Fund 556015364 001 5.6 2.3 0.2 05/31/2020 Green 03/31/2018 Green 03/31/2017 NA No West Virginia Laborers' Pension Trust Fund 556026775 001 4.5 3.0 0.5 05/31/2020 Green 03/31/2018 (a) Green 03/31/2017 NA No Laborers' National Pension Fund 751280827 001 4.1 3.5 3.0 05/31/2020 Red 12/31/2017 Green 12/31/2016 Implemented No Laborers' Pension Fund of Roanoke, Virginia 546111015 001 2.5 0.1 0.2 05/31/2020 Green 09/30/2017 Green 09/30/2016 (a) NA No IBEW Local 1249 Pension Plan 156035161 001 2.2 1.5 1.1 05/02/2021 Yellow 12/31/2017 Yellow 12/31/2016 Implemented No Ohio Operating Engineers Pension Plan 316129968 001 2.1 4.9 — 05/31/2020 Green 07/31/2017 Green 07/31/2016 NA No Laborers' Local Union No. 158 Pension Plan 236580323 001 1.5 1.8 0.4 04/30/2020 Green 12/31/2017 (a) Green 12/31/2016 NA No Employer - Teamsters Local Nos. 175 & 505 Pension Trust Fund 556021850 001 1.5 0.3 — 05/31/2020 Red 12/31/2017 (b) Red 12/31/2016 (b) Implemented No Michigan Laborers' Pension Plan 386233976 001 1.5 2.0 1.1 05/31/2020 Yellow 08/31/2018 Yellow 08/31/2017 (b) Implemented No National Electrical Benefit Fund 530181657 001 1.4 1.8 1.7 Varies through 5/31/2021 Green 12/31/2017 Green 12/31/2016 NA No Laborers' District Council of Western Pennsylvania Pension Fund 256135576 001 1.4 0.6 0.2 12/31/2020 Red 12/31/2017 Red 12/31/2016 Implemented No Operating Engineers' Local 324 Pension Fund 381900637 001 0.6 2.1 — 05/31/2020 Red 04/30/2018 Red 04/30/2017 Implemented No Other funds 15.0 (c) 10.2 (c) 12.7 (c) Total multiemployer pension plan contributions $ 92.4 $ 92.1 $ 59.9 (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 2018 , 2017 and 2016 contributions include approximately $0.2 million , $0.7 million and $0.9 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. The number of union employees employed at a given time, and the plans in which they participate, varies depending upon the location and number of ongoing projects and the need for union resources in connection with those projects. 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 2018 1,626 6,336 $ 92.4 $ 7.3 $ 99.7 2017 550 7,057 $ 92.1 $ 10.3 $ 102.4 2016 550 4,910 $ 59.9 $ 10.1 $ 70.0 The fluctuations in the number of employees covered under multiemployer plans and related contributions in the table above related primarily to timing of activity for the Company’s union resource-based projects, the majority of which are within its oil and gas operations.

Equity

Equity	12 Months Ended
	Dec. 31, 2018
Equity [Abstract]
Equity	Note 11 – Equity Share Activity The Company’s share repurchase programs provide for the repurchase of shares of MasTec common stock 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 is determined based on market conditions, legal requirements, cash flow and liquidity needs and other factors. The Company’s share repurchase programs do not have an expiration date and 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 may use either authorized and unissued shares or treasury shares to meet share issuance requirements. During the year ended December 31, 2018 , the Company repurchased approximately 7.2 million shares of its common stock for an aggregate purchase price of $319.0 million , of which approximately $5.1 million was settled in January 2019. As of December 31, 2018 , $129.4 million was available for future share repurchases under all of the Company’s open share repurchase programs. Share repurchase activity in 2018 was completed under several share repurchase programs, including: (i) 2.0 million shares repurchased for $98.4 million under a now completed $100 million share repurchase program that was established in 2016; (ii) 2.3 million shares repurchased under a separate $100 million share repurchase program that was authorized on March 29, 2018 and completed in the third quarter of 2018 ; and (iii) 2.9 million shares repurchased for $120.6 million under a $150 million share repurchase program that was authorized on September 11, 2018. As of December 31, 2018 , $29.4 million was available for future share repurchases under the September 2018 program, and $100.0 million was available under a new share repurchase program that was authorized on December 21, 2018. During the year ended December 31, 2017 , the Company repurchased 38.8 thousand shares of its common stock for an aggregate purchase price of $1.6 million under the now completed 2016 $100 million share repurchase program. No shares were repurchased during the year ended December 31, 2016 . Comprehensive Income and Accumulated Other Comprehensive 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) and related accumulated comprehensive income (loss) balances, consist 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 certain investment activities and net income (loss) attributable to non-controlling interests. Unrealized foreign currency activity for the three years in the period ended December 31, 2018 is primarily related to translation gains and losses resulting from the Company’s Canadian operations. Unrealized investment activity for the years ended December 31, 2018 and 2017 relates to unrealized gains and losses on interest rate swaps associated with the Waha JVs. A rollforward of activity within accumulated other comprehensive income (loss) for the periods indicated was as follows (in thousands): For the Years Ended December 31, 2018 2017 2016 Foreign Currency Other Total Foreign Currency Other Total Foreign Currency Other Total Balance as of January 1 $ (62,851 ) $ (861 ) $ (63,712 ) $ (64,478 ) $ (1,336 ) $ (65,814 ) $ (67,063 ) $ (5,288 ) $ (72,351 ) Unrealized (losses) gains, net of tax (2,645 ) 5,863 3,218 1,627 475 2,102 2,585 3,952 6,537 Balance as of December 31 $ (65,496 ) $ 5,002 $ (60,494 ) $ (62,851 ) $ (861 ) $ (63,712 ) $ (64,478 ) $ (1,336 ) $ (65,814 )

Income Taxes

Income Taxes	12 Months Ended
	Dec. 31, 2018
Income Tax Disclosure [Abstract]
Income Taxes	Note 12 – Income Taxes The components of income before income taxes for the periods indicated were as follows (in millions): For the Years Ended December 31, 2018 2017 2016 Domestic $ 341.1 $ 334.9 $ 202.4 Foreign 24.2 36.9 23.4 Total $ 365.3 $ 371.8 $ 225.8 The provision for income taxes for the periods indicated were as follows (in millions): For the Years Ended December 31, 2018 2017 2016 Current: Federal $ 26.7 $ (6.0 ) $ 85.8 Foreign 9.4 11.5 3.0 State and local 10.5 (0.8 ) 6.7 $ 46.6 $ 4.7 $ 95.5 Deferred: Federal $ 43.9 $ 18.2 $ 6.1 Foreign 3.3 (7.5 ) (6.8 ) State and local 12.3 7.6 (3.0 ) $ 59.5 $ 18.3 $ (3.7 ) Provision for income taxes $ 106.1 $ 22.9 $ 91.8 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, 2018 2017 Deferred tax assets: Accrued insurance $ 25.9 $ 24.6 Operating loss carryforwards and tax credits 67.7 54.9 Compensation and benefits 15.2 7.5 Bad debt 2.4 1.2 Unrealized gains and losses — 11.4 Other 8.4 7.9 Valuation allowance (40.6 ) (40.5 ) Total deferred tax assets $ 79.0 $ 67.0 Deferred tax liabilities: Property and equipment $ 146.3 $ 104.1 Goodwill 55.6 56.7 Other intangible assets 28.1 28.7 Gain on remeasurement of equity investee 7.1 6.9 Revenue recognition 21.6 11.3 Investments in unconsolidated entities 67.9 52.8 Other 16.1 11.0 Total deferred tax liabilities $ 342.7 $ 271.5 Net deferred tax liabilities $ (263.7 ) $ (204.5 ) In assessing the ability to realize the Company’s deferred tax assets, management considers whether it is more likely than not that some portion, or all, of its 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 Company’s projected future taxable income and prudent and feasible tax planning strategies in making this assessment. The Company’s valuation allowances as of December 31, 2018 and 2017 are related primarily to foreign net operating losses and deferred tax assets. The Company’s deferred tax assets for its state net operating loss carryforwards, which may be carried forward between 5 and 20 years depending on the jurisdiction, totaled approximately $11.9 million and $12.3 million as of December 31, 2018 and 2017 , respectively. The Company’s deferred tax assets for its foreign net operating loss carryforwards, which are primarily related to the Company’s Canadian operations, totaled approximately $50.8 million and $38.4 million as of December 31, 2018 and 2017 , 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 deferred tax assets for its federal net operating loss carryforwards, which begin to expire in 2022 , totaled approximately $0.2 million as of both December 31, 2018 and 2017 . 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 U.S. deferred income tax balances were adjusted in 2017 when the 2017 Tax Act was enacted. 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. Due to the complexities involved in accounting for the enactment of the 2017 Tax Act, SEC Staff Accounting Bulletin (SAB 118), which was codified in March 2018 under ASU 2018-05, Income Taxes (Topic 740): Amendments to SEC Paragraphs Pursuant to SEC Staff Accounting Bulletin No. 118 , which amended Topic 740, allowed the Company to provide a provisional estimate of the effects of the 2017 Tax Act, with a measurement period of up to one year within which to finalize such estimates. The year provided under SAB 118 to make adjustments to these initial estimates was completed for the Company on December 22, 2018, and the Company has finalized making such provisional adjustments. However, since many provisions of the 2017 Tax Act still do not have final guidance issued, it may be necessary for the Company to make future adjustments based on such new guidance. The Company recognized a net tax benefit of approximately $16.4 million for the year ended December 31, 2018 related to revisions of its initial estimates under the 2017 Tax Act, primarily from finalization of its tax return for the year ended December 31, 2017, as well as from certain tax accounting method changes and other adjustments. As of December 31, 2018 , because of the 2017 Tax Act, the Company will generally be free of additional U.S. federal tax consequences on distributed foreign subsidiary earnings due to a dividends received deduction implemented as part of the move to a territorial tax system. The Company has not made a provision for U.S. income taxes on unremitted foreign earnings because such earnings are 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, 2018 2017 2016 U.S. statutory federal rate applied to pretax income 21.0 % 35.0 % 35.0 % State and local income taxes, net of federal benefit 4.2 2.0 2.6 Foreign tax rate differential 1.5 0.3 (0.1 ) Non-deductible expenses 1.7 2.2 4.4 Goodwill and intangible assets 3.6 (0.0 ) (0.7 ) Change in tax rate (2.8 ) (32.3 ) (1.9 ) Domestic production activities deduction 0.0 (0.2 ) (2.9 ) Other (2.4 ) (0.7 ) (0.1 ) Tax credits (0.4 ) (2.8 ) (0.0 ) Valuation allowance for deferred tax assets 2.6 2.7 4.3 Effective income tax rate 29.0 % 6.2 % 40.6 % 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, 2018 2017 2016 Beginning balance $ 8.1 $ — $ — Additions based on tax positions related to the current year 2.7 3.2 — Additions for tax positions of prior years — 4.9 — Reductions for tax positions of prior years (1.4 ) — — Ending balance $ 9.4 $ 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. Accrued interest and penalties related to uncertain tax positions are $0.8 million as of December 31, 2018 , of which $0.7 million is included in income tax expense for the year ended December 31, 2018 . If the Company were to recognize its gross unrecognized tax benefits as of December 31, 2018 , approximately $9.4 million , including interest and penalties, would affect the Company’s effective tax rate. The IRS has completed its examination of the Company’s federal income tax return for the calendar year 2015 with no adjustments. The Company has been notified by the IRS that its 2016 federal income tax return will be examined. 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, 2018 , the Company is no longer subject to state examinations by taxing authorities for years before 2015 .

Segments and Related Informatio

Segments and Related Information	12 Months Ended
	Dec. 31, 2018
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 power facilities, including renewables, 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 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 businesses), and other discrete items, such as goodwill and/or 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, which is recorded within corporate results, is managed 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 the Company’s common stock or variations in the value of shares granted. Segment EBITDA is calculated in a manner consistent with consolidated EBITDA. For the year ended December 31, 2018 , Corporate EBITDA included $47.7 million of goodwill impairment charges. For the year ended December 31, 2018 , Other segment EBITDA included project gains of $1.0 million from a proportionately consolidated non-controlled Canadian joint venture, which is managed by a third party, and for which the Company has minimal direct construction involvement, whereas for the years ended December 31, 2017 and 2016 , Other segment EBITDA included project losses from this non-controlled joint venture of $7.9 million and $5.1 million , respectively. For the year ended December 31, 2016, EBITDA for the Oil and Gas and Electrical Transmission segments included certain project losses of $13.5 million and $15.1 million , respectively, and restructuring charges of $6.3 million and $8.9 million , respectively. Summarized financial information for MasTec’s reportable segments is presented and reconciled to consolidated financial information for total MasTec in the following tables, including a reconciliation of consolidated income before income taxes to EBITDA, all of which are presented in millions. The tables below may contain slight summation differences due to rounding. For the Years Ended December 31, Revenue: 2018 2017 2016 Communications (a) $ 2,556.8 $ 2,424.4 $ 2,323.6 Oil and Gas 3,288.7 3,497.2 2,024.4 Electrical Transmission 397.3 378.2 383.8 Power Generation and Industrial 665.0 299.9 405.7 Other 3.5 20.8 15.9 Eliminations (1.9 ) (13.5 ) (18.7 ) Consolidated revenue $ 6,909.4 $ 6,607.0 $ 5,134.7 (a) Revenue generated primarily by utilities customers represented 14.9% , 13.4% and 11.1% of Communications segment revenue for the years ended December 31, 2018 , 2017 and 2016 , respectively. For the Years Ended December 31, EBITDA: 2018 2017 2016 Communications $ 290.4 $ 247.4 $ 244.6 Oil and Gas 451.6 402.2 297.3 Electrical Transmission 10.5 17.6 (42.9 ) Power Generation and Industrial 40.4 22.6 18.3 Other 24.4 19.8 (2.6 ) Corporate (156.4 ) (88.7 ) (73.1 ) Consolidated EBITDA $ 660.8 $ 620.9 $ 441.5 For the Years Ended December 31, Depreciation and Amortization: 2018 2017 2016 Communications $ 59.3 $ 53.2 $ 50.3 Oil and Gas 113.7 96.7 78.4 Electrical Transmission 19.8 22.8 23.2 Power Generation and Industrial 13.7 9.1 6.2 Other 0.1 0.1 0.1 Corporate 6.3 6.1 6.7 Consolidated depreciation and amortization $ 212.9 $ 188.0 $ 164.9 As of December 31, Assets: 2018 2017 2016 Communications $ 1,461.7 $ 1,314.4 $ 1,156.9 Oil and Gas 1,965.3 1,762.6 1,267.2 Electrical Transmission 423.9 471.4 419.1 Power Generation and Industrial 358.7 288.6 268.1 Other 193.9 153.2 27.7 Corporate 36.5 76.4 44.1 Consolidated segment assets $ 4,440.0 $ 4,066.6 $ 3,183.1 For the Years Ended December 31, Capital Expenditures: 2018 2017 2016 Communications $ 69.3 $ 40.5 $ 28.5 Oil and Gas 83.5 57.7 64.0 Electrical Transmission 10.2 14.9 19.8 Power Generation and Industrial 6.5 5.4 3.4 Other 0.0 0.0 0.3 Corporate 10.9 4.9 1.1 Consolidated capital expenditures $ 180.4 $ 123.4 $ 117.1 For the Years Ended December 31, EBITDA Reconciliation: 2018 2017 2016 Income before income taxes $ 365.3 $ 371.8 $ 225.8 Plus: Interest expense, net 82.6 61.0 50.7 Depreciation and amortization 212.9 188.0 164.9 Consolidated EBITDA $ 660.8 $ 620.9 $ 441.5 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, 2018 , 2017 and 2016 , revenue of $6.7 billion , $6.4 billion and $4.9 billion , respectively, was derived from U.S. operations, and revenue of $164.3 million , $211.5 million and $279.7 million , respectively, was derived from foreign operations, the majority of which was from the Company’s Canadian operations in its Oil and Gas segment. Long-lived assets held in the U.S. included property and equipment, net, of $707.4 million , $649.5 million and $475.3 million as of December 31, 2018 , 2017 and 2016 , respectively, and, for the Company’s businesses in foreign countries, the majority of which are in Canada, totaled $40.4 million , $57.0 million and $73.8 million , respectively. Intangible assets and goodwill, net, related to the Company’s U.S. operations totaled approximately $1.2 billion as of both December 31, 2018 and 2017 , and $1.1 billion as of December 31, 2016 , and, for the Company’s businesses in foreign countries, the majority of which are in Canada, totaled approximately $61.5 million , $112.8 million and $107.8 million , respectively. As of both December 31, 2018 and 2017 , amounts due from customers from which foreign revenue was derived accounted for approximately 5% of the Company’s consolidated net accounts receivable position, which represents accounts receivable, net, less BIEC, and as of December 31, 2016 , accounted for approximately 8% of the Company’s consolidated net accounts receivable position. Significant Customers Revenue concentration information for significant customers as a percentage of total consolidated revenue was as follows: For the Years Ended December 31, 2018 2017 2016 Customer: AT&T (including DIRECTV ® ) (a) 23% 25% 34% EQT Corporation (b) 20% —% —% Energy Transfer affiliates (c) 14% 40% 27% (a) 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. (b) The Company's relationship with EQT Corporation and its affiliates is based upon various construction contracts for pipeline activities. Revenue from EQT Corporation is included in the Oil and Gas segment. (c) 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.

Commitments and Contingencies

Commitments and Contingencies	12 Months Ended
	Dec. 31, 2018
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, including project contract price and acquisition purchase price disputes. 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, 2018 and 2017 , there were $128.4 million and $157.1 million , respectively, of letters of credit issued under the Company’s credit facilities. The Company is not aware of any material claims relating to its outstanding letters of credit as of December 31, 2018 or 2017 . 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, 2018 and 2017 , outstanding performance and payment bonds approximated $123.6 million and $119.7 million , respectively, and estimated costs to complete projects secured by these bonds totaled $53.0 million and $46.0 million as of December 31, 2018 and 2017 , respectively. These amounts do not include performance and payment bonds associated with the Company’s equity investments. Investment Arrangements. The Company holds undivided interests, ranging from 85% to 90% , in multiple 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, 2018 , the Company was not aware of circumstances that would reasonably lead to material future claims against it in connection with these arrangements. Advances on project work associated with the Company’s proportionately consolidated contractual joint ventures, which are reflected within other current liabilities, totaled $7.0 million as of December 31, 2018 . The Company has other investment arrangements, under which it may incur costs or provide financing, performance, financial and/or other guarantees. See Note 4 - Fair Value of Financial Instruments and Note 15 - Related Party Transactions for additional details regarding the Company’s other investment 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, 2018 and 2017 , MasTec’s liability for unpaid claims and associated expenses, including incurred but not reported losses related to these policies, totaled $108.9 million and $106.2 million , respectively, of which $70.8 million and $72.2 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 estimated liability for employee group medical claims totaled $2.9 million and $2.6 million as of December 31, 2018 and 2017 , respectively. The Company is required to post collateral, generally in the form of letters of credit, surety bonds and cash to certain of its insurance carriers. Insurance-related letters of credit for the Company’s workers’ compensation, general liability and automobile liability policies amounted to $67.6 million and $88.9 million as of December 31, 2018 and 2017 , respectively. Outstanding surety bonds related to self-insurance programs amounted to $34.8 million and $15.2 million as of December 31, 2018 and 2017 , respectively. In addition, cash collateral deposited with insurance carriers, which is included within other long-term assets, amounted to $1.6 million for these policies as of both December 31, 2018 and 2017 . 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 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 an 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. The Company, along with other members of the Pipe Line Contractors Association, 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. In 2017, the Company recognized $0.7 million of expense in connection with the expected final settlement of the Central States withdrawal, which matter was concluded in 2018. 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 the MEPPs in which it participates. There can be no assurance, however, 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, 2018 , 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 the Company could be obligated to pay or 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, 2018 and 2017 , 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. Warranty claims are not, and have historically not been, material. 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; potential exposure to environmental liabilities; risks related to the Company’s acquisitions and investment arrangements, including acquisition integration and financing; recoverability of goodwill; exposure from system or information technology interruptions; governmental and/or regulatory changes or other factors affecting the industries in which the Company operates; collectibility of receivables and resolution of unapproved change orders; 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 470 customers for the year ended December 31, 2018 . As of December 31, 2018 , three customers each accounted for approximately 26% , 18% and 12% , respectively, of the Company’s consolidated net accounts receivable position, which represents accounts receivable, net, less BIEC. As of December 31, 2017 , two customers each accounted for approximately 46% and 15% , respectively, of the Company’s consolidated net accounts receivable position. In addition, the Company derived 72% , 78% and 76% , of its revenue from its top ten customers for the years ended December 31, 2018 , 2017 and 2016 , respectively.

Related Party Transactions

Related Party Transactions	12 Months Ended
	Dec. 31, 2018
Related Party Transactions [Abstract]
Related Party Transactions	Note 15 – Related Party Transactions MasTec purchases, rents and leases equipment and purchases various types of supplies and services used in its business from a number of different vendors on a non-exclusive basis, and from time to time, rents equipment to certain entities, including entities that are associated with members of subsidiary management. For the years ended December 31, 2018 , 2017 and 2016 , related party lease payments to such entities for operational facilities and equipment totaled approximately $46.9 million , $46.8 million and $43.3 million , respectively. Payables associated with these related party lease payments totaled approximately $1.5 million and $0.1 million as of December 31, 2018 and 2017 , respectively. Additionally, payments to such related party entities for various types of supplies and services, including ancillary construction services, project-related site restoration and marketing and business development activities totaled approximately $87.5 million , $63.9 million and $27.7 million for the years ended December 31, 2018 , 2017 and 2016 , respectively. As of December 31, 2018 and 2017 , related amounts payable totaled approximately $15.8 million and $5.2 million , respectively. Revenue from equipment rentals to such related party entities totaled approximately $0.9 million for the year ended December 31, 2018 , and related amounts receivable totaled approximately $0.2 million as of December 31, 2018 . In 2017, the Company entered into an arrangement to perform certain construction services for two entities, of which a member of subsidiary management is a minority owner. Revenue from these arrangements totaled approximately $9.4 million and $2.6 million for the years ended December 31, 2018 and 2017 , respectively. Related amounts receivable, net of BIEC, totaled approximately $0.1 million and $0.2 million for the years ended December 31, 2018 and 2017 , respectively. In 2017, MasTec acquired an oil and gas pipeline equipment company that was formerly owned by a member of subsidiary management for approximately $40.6 million in cash and an estimated earn-out liability of $75.5 million , as adjusted, of which $5.7 million was paid in the second quarter of 2018. 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, who is the brother of Jorge Mas, Chairman of MasTec’s Board of Directors, and José R. Mas, MasTec’s Chief Executive Officer, was a minority owner, for approximately $6.1 million in cash and an estimated earn-out liability of approximately $1.4 million , net, as adjusted. The net assets acquired included notes payable to the former owners totaling approximately $2.6 million , which amount was subsequently repaid. For the year ended December 31, 2018 , advances made by the Company on behalf of this entity totaled approximately $1.0 million , which amount was outstanding as of that date, and is expected to be settled under customary terms associated with the related purchase agreement. The Company rents equipment from CCI, in which it has a 15% equity investment. Juan Carlos Mas 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, 2018 , 2017 and 2016 , MasTec paid CCI approximately $57.6 million , $54.9 million and $24.5 million , net of rebates, respectively, for equipment supplies, rentals, leases and servicing. Amounts payable to CCI, net of rebates receivable, totaled approximately $4.9 million as of December 31, 2018 , and as of December 31, 2017 , were de minimis. The Company has also rented equipment to CCI. Revenue from equipment rentals to CCI totaled approximately $0.3 million for the year ended December 31, 2018 , which amount was outstanding as of December 31, 2018 . MasTec has a subcontracting arrangement 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, 2018 , 2017 and 2016 , MasTec incurred approximately $9.9 million , $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, 2018 and 2017 , related amounts payable totaled $0.4 million and $2.0 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, 2018 , 2017 and 2016 , MasTec charged approximately $0.8 million to this customer. As of December 31, 2018 and 2017 , outstanding receivables related to this employee leasing arrangement totaled approximately $0.3 million and $0.2 million , respectively. The Company also provides satellite communication services to this customer. For the years ended December 31, 2018 , 2017 and 2016 , revenue from satellite communication services provided to this customer totaled approximately $0.9 million , $0.8 million and $0.9 million , respectively. As of both December 31, 2018 and 2017 , amounts receivable from this arrangement totaled approximately $0.3 million . 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, 2018 , 2017 and 2016 , lease payments associated with this property totaled approximately $48,000 . MasTec has a leasing arrangement for an aircraft that is owned by an entity that Jorge Mas owns. For the years ended December 31, 2018 , 2017 and 2016, MasTec paid approximately $2.7 million , $2.0 million and $2.6 million , respectively, under this leasing arrangement. As of both December 31, 2018 and 2017 , related amounts payable were de minimis. The Company has a 40% interest in an entity associated with an acquisition that is accounted for as an equity method investment. The acquired business had a related party vendor financing arrangement that was completed in 2017. Payments made under this arrangement totaled $5.3 million for the year ended December 31, 2017 , with no amounts outstanding as of December 31, 2017 . Additionally, as of December 31, 2017 , there were advances outstanding from this entity, net, totaling approximately $0.3 million , which amounts were settled in 2018. The Company’s Pacer subsidiary has a subcontracting arrangement with a contractual joint venture in which it holds a 35% undivided interest. For the years ended December 31, 2018 , 2017 and 2016 , revenue recognized by the Company in connection with this arrangement totaled approximately $0.6 million , $1.5 million and $1.0 million , respectively. Accounts receivable, net of BIEC, from this contractual joint venture was de minimis as of December 31, 2018 , and totaled $0.8 million as of December 31, 2017 . Outstanding performance guarantees on behalf of this contractual joint venture totaled Canadian $26.4 million and $132.1 million as of December 31, 2018 and 2017 , respectively, or approximately $19.4 million and $105.1 million . This project was almost fully complete as of December 31, 2018 . Additionally, the Company provided project-related financing in connection with this contractual joint venture of approximately $2.7 million , $7.2 million and $6.8 million , respectively, for the years ended December 31, 2018 , 2017 and 2016 . 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. For the years ended December 31, 2018 and 2017 , the Company made distributions of earnings to holders of its non-controlling interests of $0.6 million and $1.3 million , respectively. In October 2017, the Company acquired the remaining non-controlling interests of one of these entities, with which it previously had a subcontracting arrangement for the performance of ancillary oil and gas construction services, for approximately $21.4 million in cash and an estimated earn-out liability of $9.7 million , as adjusted, of which $4.6 million was paid in 2018. Cash paid to acquire the remaining interests of this entity is reflected 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 MasTec has a split dollar life insurance agreement with (i) Jorge Mas, and José R. Mas and Juan Carlos Mas, as trustees of the Jorge Mas Irrevocable Trust (the “Jorge Mas trust”); and (ii) José R. Mas, and Jorge Mas, Juan Carlos Mas and Patricia Mas, as trustees of the José Ramon Mas Irrevocable Trust (the “José R. Mas trust”), both of which were amended and restated in February 2018. 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. The Company paid approximately $1.1 million in each of the years ended December 31, 2018 , 2017 and 2016 in connection with the split dollar agreements for Jorge Mas, and paid approximately $0.7 million in each of the years ended December 31, 2018 , 2017 and 2016 in connection with the split dollar agreements for José R. Mas. Life insurance assets associated with these agreements, which amounts are included within other long-term assets, totaled $18.5 million and $16.6 million as of December 31, 2018 and 2017 , respectively.

Quarterly Information (Unaudite

Quarterly Information (Unaudited)	12 Months Ended
	Dec. 31, 2018
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, 2018 and 2017 (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 2018 Quarters Ended For the 2017 Quarters Ended March 31 June 30 September 30 December 31 March 31 June 30 September 30 December 31 Revenue $ 1,396.8 $ 1,617.8 $ 1,977.2 $ 1,917.6 $ 1,158.2 $ 1,890.2 $ 1,955.8 $ 1,602.9 Costs of revenue, excluding depreciation and amortization $ 1,237.3 $ 1,366.6 $ 1,681.4 $ 1,654.0 $ 971.1 $ 1,626.3 $ 1,726.2 $ 1,421.7 Net income $ 26.5 $ 80.4 $ 120.5 $ 31.8 $ 40.6 $ 83.3 $ 64.2 $ 160.7 Net income attributable to MasTec, Inc. $ 26.6 $ 80.5 $ 120.7 $ 31.9 $ 41.0 $ 81.7 $ 63.8 $ 160.8 Earnings per share: Basic $ 0.33 $ 1.02 $ 1.55 $ 0.42 $ 0.51 $ 1.01 $ 0.79 $ 1.98 Diluted $ 0.32 $ 1.01 $ 1.52 $ 0.41 $ 0.50 $ 0.99 $ 0.77 $ 1.95 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) Goodwill impairment charges, pretax, totaling $47.7 million in the fourth quarter of 2018; (ii) Project gains on a proportionately consolidated non-controlled Canadian joint venture, pretax, totaling $1.0 million in the second quarter of 2018, and project losses from this non-controlled joint venture totaling $7.0 million in the first quarter of 2017; (iii) Excess tax benefit s, net, from share-based compensation of $1.3 million and $5.6 million in the fourth quarters of 2018 and 2017, respectively; (iv) Income tax effects, primarily from the 2017 Tax Act include expense of $3.7 million in the fourth quarter of 2018, benefits of $17.9 million in the third quarter of 2018, expense of $1.5 million in the second quarter of 2018 and benefits of $120.1 million in the fourth quarter of 2017, respectively.

Supplemental Guarantor Financia

Supplemental Guarantor Financial Information	12 Months Ended
	Dec. 31, 2018
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, 2018 , 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, 2018 MasTec, Inc. Guarantor Subsidiaries Non-Guarantor Subsidiaries Eliminations Consolidated MasTec, Inc. Revenue $ — $ 6,539.3 $ 492.6 $ (122.5 ) $ 6,909.4 Costs of revenue, excluding depreciation and amortization — 5,609.4 452.4 (122.5 ) 5,939.3 Depreciation and amortization — 190.5 22.4 — 212.9 Goodwill impairment — — 47.7 — 47.7 General and administrative expenses 3.1 266.4 17.8 — 287.3 Interest expense (income), net — 147.0 (64.4 ) — 82.6 Equity in earnings of unconsolidated affiliates — — (23.9 ) — (23.9 ) Other expense (income), net — 2.9 (4.7 ) — (1.8 ) (Loss) income before income taxes $ (3.1 ) $ 323.1 $ 45.3 $ — $ 365.3 Benefit from (provision for) income taxes 0.9 (94.2 ) (12.8 ) — (106.1 ) Net (loss) income before equity in income from subsidiaries $ (2.2 ) $ 228.9 $ 32.5 $ — $ 259.2 Equity in income from subsidiaries, net of tax 261.9 — — (261.9 ) — Net income (loss) $ 259.7 $ 228.9 $ 32.5 $ (261.9 ) $ 259.2 Net loss attributable to non-controlling interests — — (0.4 ) — (0.4 ) Net income (loss) attributable to MasTec, Inc. $ 259.7 $ 228.9 $ 32.9 $ (261.9 ) $ 259.7 Comprehensive income (loss) $ 262.9 $ 228.9 $ 35.7 $ (265.1 ) $ 262.4 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 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 CONDENSED CONSOLIDATING BALANCE SHEETS (in millions) As of December 31, 2018 MasTec, Inc. Guarantor Subsidiaries Non-Guarantor Subsidiaries Eliminations Consolidated MasTec, Inc. Assets Total current assets $ — $ 1,993.0 $ 248.5 $ (72.5 ) $ 2,169.0 Property and equipment, net — 699.2 48.6 — 747.8 Goodwill and other intangible assets, net — 1,188.0 81.7 — 1,269.7 Investments in and advances to consolidated affiliates, net 1,373.1 1,138.4 816.9 (3,328.4 ) — Other long-term assets 16.8 42.0 194.6 — 253.4 Total assets $ 1,389.9 $ 5,060.6 $ 1,390.3 $ (3,400.9 ) $ 4,440.0 Liabilities and equity Total current liabilities $ — $ 1,185.9 $ 170.2 $ (72.5 ) $ 1,283.6 Long-term debt — 1,319.4 4.9 — 1,324.2 Other long-term liabilities — 429.2 10.8 — 440.1 Total liabilities $ — $ 2,934.5 $ 185.9 $ (72.5 ) $ 3,047.9 Total equity $ 1,389.9 $ 2,126.1 $ 1,204.4 $ (3,328.4 ) $ 1,392.0 Total liabilities and equity $ 1,389.9 $ 5,060.6 $ 1,390.3 $ (3,400.9 ) $ 4,440.0 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 CONDENSED CONSOLIDATING STATEMENTS OF CASH FLOWS (in millions) For the Year Ended December 31, 2018 MasTec, Inc. Guarantor Subsidiaries Non-Guarantor Subsidiaries Eliminations Consolidated MasTec, Inc. Net cash provided by operating activities $ — $ 341.6 $ 188.4 $ — $ 530.0 Cash flows from investing activities: Cash paid for acquisitions, net of cash acquired — (6.7 ) — — (6.7 ) Capital expenditures — (174.3 ) (6.1 ) — (180.4 ) Proceeds from sale of property and equipment — 26.2 13.1 — 39.4 Payments for other investments — (11.8 ) (27.6 ) — (39.5 ) Proceeds from other investments — — 5.4 — 5.4 Net cash used in investing activities $ — $ (166.6 ) $ (15.2 ) $ — $ (181.8 ) Cash flows from financing activities: Proceeds from credit facilities — 3,383.9 34.3 — 3,418.2 Repayments of credit facilities — (3,314.8 ) (44.7 ) — (3,359.5 ) Repayments of other borrowings and capital lease obligations, net — (83.7 ) (5.9 ) — (89.6 ) Payments of acquisition-related contingent consideration — (15.9 ) — — (15.9 ) Payments to non-controlling interests, including acquisition of interests and distributions — (0.6 ) — — (0.6 ) Proceeds from stock-based awards, net 0.2 — — — 0.2 Repurchase of common stock (313.9 ) — — — (313.9 ) Other financing activities, net — — — — — Net financing activities and advances from (to) consolidated affiliates 313.7 (142.1 ) (171.6 ) — — Net cash used in financing activities $ — $ (173.2 ) $ (187.9 ) $ — $ (361.1 ) Effect of currency translation on cash — — — — — Net increase (decrease) in cash and cash equivalents $ — $ 1.8 $ (14.7 ) $ — $ (12.9 ) Cash and cash equivalents - beginning of period — 10.1 30.3 — 40.3 Cash and cash equivalents - end of period $ — $ 11.9 $ 15.6 $ — $ 27.4 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 $ — $ 142.9 $ 1.2 $ — $ 144.1 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 — (6.6 ) — — (6.7 ) 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 $ — $ 58.8 $ 71.5 $ — $ 130.3 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 CONDENSED CONSOLIDATING STATEMENTS OF CASH FLOWS (in millions) 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

Schedule II - Valuation and Qua

Schedule II - Valuation and Qualifying Accounts	12 Months Ended
	Dec. 31, 2018
SEC Schedule, 12-09, 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, 2018 Allowance for doubtful accounts $ 8.2 $ 8.6 (a) $ — $ (0.5 ) (b) $ 16.3 Costs and earnings in excess of billings allowance 27.2 33.0 (a) — (38.2 ) (b) 22.0 Valuation allowance for inventory 7.7 1.1 (c) — (1.0 ) (d) 7.8 Valuation allowance for deferred tax assets 40.5 0.1 (e) — — 40.6 Total $ 83.6 $ 42.8 $ — $ (39.7 ) $ 86.7 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 Valuation allowance for inventory 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 Valuation allowance for inventory 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 (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) Provisions for obsolete inventory and other adjustments to net realizable value. (d) Inventory write-offs. (e) Additions related to federal, foreign, and state attributes. (f) Additions related to unrealized gains and losses.

Business, Basis of Presentati_2

Business, Basis of Presentation and Significant Accounting Policies (Policies)	12 Months Ended
	Dec. 31, 2018
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 either the equity method of accounting or under the fair value option. 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.
Reclassifications	When necessary, certain prior year amounts have been reclassified to conform with the current period presentation.
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 included 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 cost-to-cost method, for which the recorded amounts require estimates of costs to complete and the amount of variable consideration included in the contract transaction price; allowances for doubtful accounts; fair value estimates, including those related to 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 The Company adopted the requirements of Accounting Standards Update (“ASU”) 2014-09, Revenue from Contracts with Customers , which is also referred to as Accounting Standards Codification (“ASC”) Topic 606 (“Topic 606”), under the modified retrospective transition approach effective January 1, 2018, with application to all existing contracts that were not substantially completed as of January 1, 2018. The difference between the recognition criteria under Topic 606 and the Company’s previous revenue recognition practices under the previous revenue recognition guidance, ASC Topic 605-35, was recognized through a cumulative effect adjustment of approximately $2 million that was made to the opening balance of retained earnings as of January 1, 2018. Consistent with the modified retrospective transition approach, the comparative 2017 prior period was not adjusted to conform to the current period presentation. Under Topic 606, revenue is recognized when, or as, control of promised goods and services is transferred to customers, and the amount of revenue recognized reflects the consideration to which an entity expects to be entitled in exchange for the goods and services transferred. The adoption of Topic 606 did not have a material effect on the timing or amount of revenue recognized as compared with the Company’s previous revenue recognition practices. Revenue is primarily recognized by the Company over time utilizing the cost-to-cost measure of progress, which is an input method, on contracts for specific projects, and for certain master service and other service agreements, consistent with the Company’s previous revenue recognition practices. Under Topic 606, the cost-to-cost measure of progress best depicts the continuous transfer of control of goods or services to the customer, and correspondingly, when performance obligations are satisfied, for these contracts. Contracts. The Company derives revenue primarily from construction projects performed under: (i) master and other service agreements, which provide a menu of available services in a specific geographic territory that are utilized on an as-needed basis, and are typically priced using time and materials or a fixed price per unit basis; or (ii) contracts for specific projects requiring the construction and installation of an entire infrastructure system or specified units within an infrastructure system, which are subject to multiple pricing options, including fixed price, unit price, time and materials, or cost plus a markup. Revenue derived from projects performed under master service and other service agreements totaled 35% , 36% and 43% of consolidated revenue for the years ended December 31, 2018 , 2017 and 2016 , respectively. Fixed price contracts provide for a fixed amount of revenue for the entire project. Revenue from these contracts, as well as for certain projects pursuant to master and other service agreements, is recognized over time using the cost-to-cost measure of progress. For these contracts, the cost-to-cost measure of progress best depicts the continuous transfer of control of goods or services to the customer. Such contracts provide that the customer accept completion of progress to date and compensate the Company for services rendered. For certain master service and other service agreements under which the Company performs installation and maintenance services, primarily for install-to-the-home service providers in its Communications segment, revenue is recognized at a point in time. This is generally when the work order has been fulfilled, which is typically the same day the work is initiated. Point in time revenue accounted for approximately 7% of consolidated revenue for the year ended December 31, 2018 . Substantially all of the Company’s other revenue is recognized over time. Contract costs include all direct materials, labor and subcontracted costs, as well as indirect costs related to contract performance, such as indirect labor, supplies, tools, repairs and the operational costs of capital equipment. The cost estimation process for recognizing revenue over time under the cost-to-cost method is based on the professional knowledge and experience of the Company’s project managers, engineers and financial professionals. Management reviews estimates of total contract transaction price and total project costs on an ongoing basis. Changes in job performance, job conditions and management’s assessment of expected variable consideration are factors that influence estimates of the total contract transaction price, total costs to complete those contracts and the Company’s profit recognition. Changes in these factors could result in revisions to revenue in the period in which the revisions are determined, which could materially affect the Company’s consolidated results of operations for that period. Provisions for losses on uncompleted contracts are recorded in the period in which such losses are determined. For both the years ended December 31, 2018 and 2017 , 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, 2017 and 2016 . Revenue recognized for the year ended December 31, 2018 as a result of changes in revenue estimates, including from variable consideration, from performance obligations satisfied, or partially satisfied, in prior periods totaled approximately $38.5 million . The Company may incur certain costs that can be capitalized, such as initial set-up or mobilization costs. Such costs, which are amortized over the life of the respective project, were not material for the year ended December 31, 2018 . The timing of customer billings is generally dependent upon advance billing terms, milestone billings based on completion of certain phases of work, or when services are provided. Under the typical payment terms of master and other service agreements and fixed price contracts, the customer makes progress payments based on quantifiable measures of performance by the Company as defined by each specific agreement. Progress payments, generally net of amounts retained, are paid by the customer over the duration of the contract. For install-to-the-home contracts, work orders are billed and paid as completed. Amounts billed and due from customers, as well as the amount of contract assets, are classified within accounts receivable, net, in the consolidated balance sheets. See Note 5 - Accounts Receivable, Net of Allowance, and Contract Assets and Liabilities for related discussion. Amounts expected to be collected beyond one year are classified as other long-term assets. Performance Obligations. A performance obligation is a contractual promise to transfer a distinct good or service to a customer, and is the unit of account under Topic 606. The transaction price of a contract is allocated to each distinct performance obligation and recognized as revenue when or as the performance obligation is satisfied. The Company’s contracts often require significant services to integrate complex activities and equipment into a single deliverable, and are therefore generally accounted for as a single performance obligation, even when delivering multiple distinct services. Contract amendments and change orders, which are generally not distinct from the existing contract, are typically accounted for as a modification of the existing contract and performance obligation. The vast majority of the Company’s performance obligations are completed within one year . When more than one contract is entered into with a customer on or close to the same date, the Company evaluates whether those contracts should be combined and accounted for as a single contract, as well as whether those contracts should be accounted for as one, or more than one, performance obligation. This evaluation requires significant judgment and is based on the facts and circumstances of the various contracts. Remaining performance obligations represent the amount of unearned transaction price under contracts for which work is wholly or partially unperformed, including the Company’s share of unearned transaction price from its proportionately consolidated non-controlled joint ventures. As of December 31, 2018 , the amount of the Company’s remaining performance obligations was $5.0 billion . The Company expects to recognize approximately $4.3 billion of its remaining performance obligations as revenue during 2019 , with the remainder to be recognized primarily in 2020 . Variable Consideration. Transaction prices for the Company’s contracts may include variable consideration, which comprises items such as change orders, claims and incentives. Management estimates variable consideration for a performance obligation utilizing estimation methods that it believes best predict the amount of consideration to which the Company will be entitled. Variable consideration is included in the estimated transaction price if it is probable that when the uncertainty associated with the variable consideration is resolved, there will not be a significant reversal of the cumulative amount of revenue that has been recognized. Management’s estimates of variable consideration and the determination of whether to include estimated amounts in the transaction price are based largely on engineering studies and legal opinions, past practices with the customer, specific discussions, correspondence or preliminary negotiations with the customer and all other relevant information that is reasonably available at the time of the estimate. The effect of variable consideration on the transaction price of a performance obligation is typically recognized as an adjustment to revenue on a cumulative catch-up basis, as such variable consideration, which typically pertains to changed conditions and scope, is generally for services encompassed under the existing contract. To the extent unapproved change orders, claims and other variable consideration reflected in transaction prices are not resolved in the Company’s favor, or to the extent incentives reflected in transaction prices are not earned, there could be reductions in, or reversals of, previously recognized revenue. As of December 31, 2018 and 2017 , the Company included approximately $56 million and $146 million , respectively, of change orders and/or claims in the transaction price for certain contracts that were in the process of being resolved in the normal course of business, including through negotiation, arbitration and other proceedings. These transaction price adjustments are included within costs and earnings in excess of billings or accounts receivable, net of allowance, as appropriate. As of both December 31, 2018 and 2017 , these change orders and/or claims were primarily related to certain pipeline construction projects in the Oil and Gas segment. The Company actively engages with its customers to complete the final approval process, and generally expects these processes to be completed within one year . Amounts ultimately realized upon final acceptance by customers could be higher or lower than such estimated amounts.
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 anticipated losses on its accounts receivable balances either when a business unit has historical experience of losses that are considered to be ordinary course, and/or for specific receivables, when it is probable that the 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.
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 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. The value of inventory may also decrease due to obsolescence, physical deterioration, damage, changes in price levels, or other causes. Inventory valuation allowances are determined based upon specific facts and circumstances and market conditions.
Cash and Cash Equivalents	Cash and Cash Equivalents Cash consisting of interest-bearing demand deposits is carried at cost, which approximates fair value. Highly liquid investments purchased with an original maturity of three months or less 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, 2018 and 2017 are amounts held by entities that are proportionately consolidated totaling $11.8 million and $17.3 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.
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 the amount 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, and outstanding balances on its credit facilities approximate their fair values.
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, 2018 , the Company determined that certain of its investment arrangements were VIEs. The Company does not, however, have the power to direct the primary activities that most significantly impact the economic performance of these VIEs and the Company is not the primary beneficiary; accordingly, it has not consolidated these VIEs.
Equity Method Investments	The Company’s investments in entities for which the Company does not have a controlling interest and for which it is not the primary beneficiary, but for which it has the ability to exert significant influence, are accounted for using either the equity method of accounting or under the fair value option. 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. Distributions received from equity method investees are reflected in the statements of cash flows using the nature of distributions approach, under which distributions are classified based on the nature of the activity that generated them.
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.
Other Equity Investments With Readily Determinable Fair Values	Under the new guidance, which was applicable to the Company on a prospective basis, e quity investments, other than those accounted for as equity method investments or those that are proportionately consolidated, are measured at fair value if their fair values are readily determinable.
Other Equity Investments Without Readily Determinable Fair Values	Equity investments that do not have readily determinable fair values are measured at cost, adjusted for changes from observable market transactions, less impairment (“adjusted cost basis”). The Company evaluates its investments for impairment by considering a variety of factors, including the earnings capacity of the related investments. Fair value measurements for the Company’s equity investments are classified within Level 3 of the fair value hierarchy based on the nature of the fair value inputs. Realized and unrealized gains or losses are recognized in other income or expense.
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 that extend the life of the related assets 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 revenue and operating costs for the business as well as anticipated future economic conditions. 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, monitors these assets for potential indicators of impairment. 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. If two or more components are deemed economically similar, those components are aggregated into one reporting unit when performing the annual goodwill impairment test.
Business Combinations	Business Combinations 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. 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, or based on the final net assets and working capital of the acquired business, as prescribed in the applicable purchase agreement. Such adjustments may result in the recognition, or adjust the fair values, of acquisition-related assets and liabilities and/or consideration paid, and are referred to as “measurement period” adjustments. Other revisions to these fair value estimates are reflected as income or expense, as appropriate. 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-outs.” Earn-out liabilities are measured at their estimated fair values as of the date of acquisition. Subsequent to the date of acquisition, if future earn-out payments are expected to differ from earn-out payments estimated as of the date of acquisition, any related fair value adjustments are recognized in the period that such expectation is considered probable. Changes in the fair value of earn-out liabilities, other than those related to measurement period adjustments, as described above, are recorded within other income or expense in the consolidated statements of operations. Fair values are estimated using income approaches such as discounted cash flows or option pricing models. Acquisition-related contingent consideration is included within other current and other long-term liabilities, as appropriate, within the consolidated balance sheets.
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 deductions from the carrying amounts 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. In addition, the Company has excess umbrella coverage. 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 estimated 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 required to post collateral, generally in the form of letters of credit, surety bonds and cash to certain of its insurance carriers. 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. These insurance liabilities are, however, difficult to assess and estimate due to many factors, the effects of which are often unknown or difficult to estimate, including the severity of an injury, the determination of the Company’s liability in proportion to other parties’ liability 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 consequences 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, net, within the consolidated balance sheets as 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 any related valuation allowances. 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. As a result of the 2017 Tax Act, the Company will generally be free of additional U.S. federal tax consequences on distributed foreign subsidiary earnings due to a dividends received deduction implemented as part of the move to a territorial tax system. The Company has generally not provided for U.S. income taxes on unremitted foreign earnings because such earnings are considered to be insignificant. 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 included broad tax reform that was applicable to the Company. See Note 12 - Income Taxes for additional discussion. 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 Company’s consolidated financial statements, which could materially affect the Company’s results of operations, cash flows and liquidity 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	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 participants. 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 tax effects of differences between the fair value of a share-based award on the date of vesting and the date of grant, also referred to as excess tax benefits or tax deficiencies, are recognized within the provision for income taxes in the period such vestings occur. 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, some of the underlying shares may be sold to cover the required tax withholdings. 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. Withheld shares, which are valued at the market price on the date of vesting, are recorded as a reduction to additional paid-in capital and are reflected within financing activities in the consolidated statements of cash flows. Shares withheld in connection with stock-based compensation arrangements totaled approximately 96,739 , 138,519 , and 44,988 for the years ended December 31, 2018 , 2017 and 2016 , respectively, and payments to taxing authorities for withheld shares totaled $3.8 million , $6.2 million and $0.6 million , respectively. The Company has certain employee stock purchase plans (collectively, “ESPPs”) under which shares of the Company’s common stock are available for purchase by eligible participants. These plans allow participants 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 IRS may impose on the employers contributing to such plans 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 the Company refers 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.
Recent Accounting Pronouncements	Recent Accounting Pronouncements See the revenue recognition discussion within Significant Accounting Policies above, and the recent accounting pronouncements discussion below, for information pertaining to the effects of recently adopted and other recent accounting pronouncements. Other Accounting Pronouncements Adopted in 2018 In August 2016, the Financial Accounting Standards Board (“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 resulted in the reclassification of $12 million of acquisition-related contingent consideration payments in excess of acquisition date liabilities from financing to operating cash flows for the year ended December 31, 2017. The other provisions of this ASU did not have a material effect on the Company’s consolidated financial statements. Accounting Pronouncements To Be Adopted in 2019 In February 2016, the FASB issued ASU 2016-02, Leases (Topic 842), which, together with its related clarifying ASUs (collectively, “ASU 2016-02”), provides revised guidance for lease accounting and related disclosure requirements, including a requirement for lessees to recognize right-of-use assets and lease liabilities on the balance sheet for leases with durations greater than twelve months. Under the new guidance, lessees will classify leases as either finance or operating leases. Lease expense is recognized based on an effective interest method for finance leases, and on a straight-line basis over the term of the lease for operating leases. The new guidance is effective for fiscal years, and for interim periods within those fiscal years, beginning after December 15, 2018. The Company will adopt ASU 2016-02 during the first quarter of 2019 using the modified retrospective method. The new guidance will be applied to leases that exist or are entered into on or after January 1, 2019, without adjusting comparative periods in the financial statements. The Company elected to utilize the package of practical expedients that allows entities to (1) not reassess whether any expired or existing contracts are or contain leases; (2) retain the existing classification of lease contracts as of the date of adoption; and (3) not reassess initial direct costs for any existing leases. The Company is in the final stages of evaluating its existing lease portfolio and is continuing to assess and quantify the value of right-of-use assets and lease liabilities that will be included on its balance sheet as of January 1, 2019. The Company is finalizing its implementation of a new lease accounting and administration software solution to manage and account for leases under the new guidance and is updating certain of its business processes and internal controls to meet the reporting and disclosure requirements of the new standard. The new guidance is not expected to materially affect the amount of expense recognized under the Company’s current leasing arrangements, however, based on its review to date of existing lease contracts, the Company expects the amount of incremental lease assets and liabilities to be recognized on its consolidated balance sheets for operating leases will be between $200 million and $230 million . The adoption of Topic 842 is not expected to have a material effect on the Company's results of operations or cash flows. For information about the Company’s future lease commitments as of December 31, 2018, see Note 8 - Lease Obligations . In August 2018, the SEC issued Release No. 33-10532, Disclosure Update and Simplification , which amends and clarifies certain financial reporting disclosure requirements. The principal change from this new guidance will be the inclusion of a statement of changes in shareholders' equity in the Company’s interim consolidated financial statements beginning with the quarter ended March 31, 2019. In June 2018, the FASB issued ASU 2018-07, Compensation-Stock Compensation (Topic 718) - Improvements to Nonemployee Share-Based Payment Accounting (“ASU 2018-07”). ASU 2018-07 expands the guidance in Topic 718 to include share-based payments for goods and services to non-employees and generally aligns it with the guidance for share-based payments to employees. ASU 2018-07 is effective for fiscal years, and for interim periods within those fiscal years, beginning after December 15, 2018, with early adoption permitted. The adoption of this ASU is not expected to have a material effect on the Company’s consolidated financial statements. 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. The Company will adopt ASU 2018-02 during the first quarter of 2019 and continues to evaluate its policy election and the related effect of this ASU on its consolidated financial statements, which is not expected to be material. Other Recent Accounting Pronouncements In August 2018, the FASB issued ASU 2018-15, Intangibles-Goodwill and Other-Internal-Use Software (Subtopic 350-40) Customer’s Accounting for Implementation Costs Incurred in a Cloud Computing Arrangement That Is a Service Contract (“ASU 2018-15”) to reduce diversity in practice in accounting for the costs of implementing cloud computing arrangements that are service contracts. ASU 2018-15 aligns the requirements for capitalizing implementation costs incurred in a cloud computing arrangement that is a service contract with the requirements for internal-use software. Accounting for the service element of the cloud computing arrangement is not affected by the new guidance. Under ASU 2018-15, amortization expense, payments for and asset balances related to such capitalized implementation costs are to be presented within the same line items of the entity’s statements of operations, cash flows and balance sheets, respectively, as the related service fee activity and balances would be presented. ASU 2018-15 i s effective for fiscal years, and for interim periods within those fiscal years, beginning after December 15, 2019, with early adoption permitted. The Company is currently evaluating the potential effect of this ASU on its consolidated financial statements. In August 2018, the FASB issued ASU 2018-13, Fair Value Measurement (Topic 820) Disclosure Framework - Changes to the Disclosure Requiremen ts for Fair Value Measurement (“ASU 2018-13”). ASU 2018-13, which is intended to improve the effectiveness of fair value measurement disclosures, modifies the disclosure requirements for certain estimates and assumptions used in determining the fair value of assets and liabilities. ASU 2018-13 i s effective for fiscal years, and for interim periods within those fiscal years, beginning after December 15, 2019, with early adoption permitted. The Company is currently evaluating the potential effect of this ASU on its consolidated financial statements. In June 2016, the FASB issued ASU 2016-13, Financial Instruments - Credit Losses (Topic 326), Measurement of Credit Losses on Financial Instruments (“ASU 2016-13”). ASU 2016-13 introduced an expected credit loss methodology for the measurement and recognition of credit losses on most financial assets, including trade and financing receivables. The expected credit loss methodology under ASU 2016-13, which is based on historical experience, current conditions and reasonable and supportable forecasts, replaces the probable/incurred loss model for measuring and recognizing expected losses under current GAAP. ASU 2016-13 also requires enhanced disclosures pertaining to significant estimates and judgments used in estimating credit losses under the expected credit loss methodology. ASU 2016-13 and its related clarifying assumptions are effective for fiscal years, and for interim periods within those fiscal years, beginning after December 15, 2019, with early adoption permitted. The Company is currently evaluating the potential effect of this ASU on its consolidated financial statements.
Comprehensive Income	Comprehensive Income and Accumulated Other Comprehensive 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) and related accumulated comprehensive income (loss) balances, consist 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 certain 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)

Earnings Per Share (Tables)	12 Months Ended
	Dec. 31, 2018
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, 2018 2017 2016 Net income attributable to MasTec: Net income - basic and diluted (a) $ 259,659 $ 347,213 $ 131,263 Weighted average shares outstanding: Weighted average shares outstanding - basic 78,695 80,903 80,372 Dilutive common stock equivalents 1,077 1,422 1,022 Weighted average shares outstanding - diluted 79,772 82,325 81,394 (a) Calculated as total net income less amounts attributable to non-controlling interests.

Goodwill and Other Intangible_2

Goodwill and Other Intangible Assets (Tables)	12 Months Ended
	Dec. 31, 2018
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, 2016 $ 420.7 $ 377.6 $ 149.9 $ 117.6 $ 1,065.8 Accumulated impairment loss (a) — (69.9 ) — — (69.9 ) 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 Additions from new business combinations — — — 9.8 9.8 Measurement period adjustments, net (b) 1.4 5.7 — (2.5 ) 4.6 Goodwill impairment — (47.7 ) — — (47.7 ) Currency translation adjustments — (4.0 ) — — (4.0 ) Goodwill, net, as of December 31, 2018 $ 467.8 $ 339.6 $ 149.9 $ 143.1 $ 1,100.4 Accumulated impairment loss (a) — (116.0 ) — — (116.0 ) Goodwill, gross, as of December 31, 2018 $ 467.8 $ 455.6 $ 149.9 $ 143.1 $ 1,216.4 (a) Accumulated impairment losses include the effects of currency translation gains and/or losses. (b) Represents adjustments to preliminary estimates of fair value within the measurement period of up to one year from the date of acquisition.
Rollforward of Other Intangible Assets	The following table provides a reconciliation of changes in other intangible assets, net, 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, 2016 $ 34.5 $ 74.6 $ 195.1 $ 19.1 $ 323.3 Accumulated amortization (131.9 ) (11.7 ) (143.6 ) 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 Additions from new business combinations — — 3.3 0.3 3.6 Measurement period adjustments (b) — — — (0.7 ) (0.7 ) Amortization expense (19.2 ) (1.4 ) (20.6 ) Currency translation adjustments — (3.6 ) (0.3 ) (0.1 ) (4.0 ) Other intangible assets, net, as of December 31, 2018 $ 34.5 $ 74.0 $ 54.4 $ 6.5 $ 169.4 Remaining weighted average amortization period (in years) 8 7 8 (a) Consists principally of trade names and non-compete agreements. (b) Represents adjustments to preliminary estimates of fair value within the measurement period of up to one year from the date of acquisition.
Schedule of Expected Future Amortization Expense	Expected future amortization expense as of December 31, 2018 is summarized in the following table (in millions): Amortization Expense 2019 $ 14.6 2020 11.2 2021 8.5 2022 6.9 2023 4.9 Thereafter 14.8 Total $ 60.9
Schedule of Consideration Paid and Net Assets Acquired, Business Combinations	The following table summarizes the fair values of consideration paid and net assets acquired as of the respective dates of acquisition, as adjusted (in millions): Acquisition consideration: 2017 Cash $ 120.4 Estimated fair value of contingent consideration (earn-out liability) 98.5 Total consideration transferred $ 218.9 Identifiable assets acquired and liabilities assumed: Current assets, primarily composed of accounts receivable and $2.8 million of cash acquired $ 43.8 Property and equipment and other long-term assets 57.2 Amortizing intangible assets 28.1 Current liabilities, including current portion of capital lease obligations and long-term debt (29.5 ) Long-term debt, including capital lease obligations (9.9 ) Deferred income taxes and other long-term liabilities (12.0 ) Total identifiable net assets $ 77.7 Goodwill $ 141.2 Total net assets acquired, including goodwill $ 218.9

Fair Value of Financial Instr_2

Fair Value of Financial Instruments (Tables)	12 Months Ended
	Dec. 31, 2018
Fair Value Disclosures [Abstract]
Schedule of Summarized Financial Information of Equity Method Investments	The following presents summarized information for the Company’s significant equity method investments (in millions): December 31, 2018 2017 Current assets $ 137.3 $ 136.8 Long-term assets 1,352.1 1,306.3 Total assets $ 1,489.4 $ 1,443.1 Current liabilities $ 31.3 $ 121.2 Long-term liabilities 966.1 976.5 Total liabilities $ 997.4 $ 1,097.7 For the Years Ended December 31, 2018 2017 2016 Revenue $ 145.8 $ 114.5 $ — Net income (loss) $ 72.4 $ 64.5 $ (0.2 )

Accounts Receivable, Net of A_2

Accounts Receivable, Net of Allowance, and Contract Assets and Liabilities (Tables) - Accounts Receivable [Member]	12 Months Ended
	Dec. 31, 2018
Schedule of Accounts Receivable, Net of Allowance, and Contract Assets [Line Items]
Schedule of Accounts Receivable, Net of Allowance, and Contract Assets	The following table provides details of accounts receivable, net of allowance, and contract assets (together, “accounts receivable, net”) as of the dates indicated (in millions): December 31, 2018 2017 Contract billings $ 687.6 $ 683.9 Less allowance for doubtful accounts (16.3 ) (8.2 ) Accounts receivable, net of allowance $ 671.3 $ 675.7 Retainage 230.2 323.1 Costs and earnings in excess of billings 1,022.5 599.2 Retainage and costs and earnings in excess of billings (together, "contract assets") $ 1,252.7 $ 922.3 Accounts receivable, net $ 1,924.0 $ 1,598.0
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, 2018 2017 Allowance for doubtful accounts at beginning of year $ 8.2 $ 8.4 Provision for doubtful accounts 8.6 2.6 Amounts charged against the allowance (0.5 ) (2.8 ) Allowance for doubtful accounts at end of year $ 16.3 $ 8.2

Property and Equipment, Net (Ta

Property and Equipment, Net (Tables)	12 Months Ended
	Dec. 31, 2018
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, 2018 2017 Estimated Useful Lives (in years) Land $ 4.6 $ 4.6 Buildings and leasehold improvements 30.3 26.7 3-40 Machinery and equipment 1,391.8 1,261.9 2-20 Office furniture and equipment 166.7 149.9 3-7 Construction in progress 20.1 12.5 Total property and equipment $ 1,613.5 $ 1,455.6 Less accumulated depreciation and amortization (865.7 ) (749.1 ) Property and equipment, net $ 747.8 $ 706.5

Debt (Tables)

Debt (Tables)	12 Months Ended
	Dec. 31, 2018
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 2018 2017 Senior secured credit facility: February 22, 2022 Revolving loans $ 456.9 $ 377.7 Term loan 376.9 396.9 4.875% Senior Notes March 15, 2023 400.0 400.0 Capital lease obligations, weighted average interest rate of 3.9% In installments through December 31, 2023 183.2 181.2 Other debt obligations — 25.8 Total long-term debt obligations $ 1,417.0 $ 1,381.6 Less unamortized deferred financing costs (10.1 ) (13.0 ) Total debt, net of deferred financing costs $ 1,406.9 $ 1,368.6 Current portion of long-term debt 82.7 87.9 Long-term debt $ 1,324.2 $ 1,280.7
Schedule of Contractual Maturities of Debt and Capital Lease Obligations	Contractual maturities of MasTec’s debt and capital lease obligations as of December 31, 2018 were as follows (in millions): 2019 $ 83.1 2020 76.2 2021 63.4 2022 792.9 2023 401.4 Thereafter — Total $ 1,417.0

Lease Obligations (Tables)

Lease Obligations (Tables)	12 Months Ended
	Dec. 31, 2018
Leases [Abstract]
Schedule of Future Lease Commitments	Future minimum lease commitments under capital leases and non-cancelable operating leases, including escalation clauses in effect as of December 31, 2018 , were as follows (in millions): Capital Leases Operating Leases 2019 $ 68.2 $ 86.4 2020 60.2 60.4 2021 46.7 37.1 2022 20.0 21.7 2023 1.5 12.1 Thereafter — 21.8 Total minimum lease payments $ 196.6 $ 239.5 Less amounts representing interest (13.4 ) Total capital lease obligations, net of interest $ 183.2 Less current portion (63.1 ) Long-term portion of capital lease obligations, net of interest $ 120.1

Stock-Based Compensation and _2

Stock-Based Compensation and Other Employee Benefit Plans (Tables)	12 Months Ended
	Dec. 31, 2018
Share-based Compensation [Abstract]
Schedule of Activity, Restricted Shares	Activity, restricted shares: (a) Restricted Per Share Weighted Average Grant Date Fair Value 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 Granted 423,596 41.41 Vested (554,900 ) 17.73 Canceled/forfeited (47,054 ) 22.26 Non-vested restricted shares, as of December 31, 2018 1,270,233 $ 31.80 (a) Includes 18,700 , 27,550 and 43,300 restricted stock units as of December 31, 2018 , 2017 and 2016 , respectively.
Schedule of 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, 2018 2017 2016 Cash proceeds (in millions) $ 4.2 $ 3.3 $ 2.7 Common shares issued 110,506 92,145 144,183 Weighted average price per share $ 37.98 $ 35.92 $ 18.55 Weighted average per share grant date fair value $ 9.36 $ 9.24 $ 5.00

Other Retirement Plans (Tables)

Other Retirement Plans (Tables)	12 Months Ended
	Dec. 31, 2018
Multiemployer Plans [Line Items]
Schedule of Covered Employees and Contributions, Multiemployer 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 2018 1,626 6,336 $ 92.4 $ 7.3 $ 99.7 2017 550 7,057 $ 92.1 $ 10.3 $ 102.4 2016 550 4,910 $ 59.9 $ 10.1 $ 70.0
Multiemployer Plans, Pension [Member]
Multiemployer Plans [Line Items]
Schedule of Multiemployer Pension Plans	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 2018 2017 2016 Expiration Date of CBA 2018 As of 2017 As of FIP/RP Status Surcharge Pipeline Industry Pension Fund 736146433 001 $ 20.7 $ 28.8 $ 15.9 05/31/2020 Green 12/31/2017 (a) Green 12/31/2016 (a) NA No Central Pension Fund of the IUOE & Participating Employers 366052390 001 20.4 21.6 19.3 05/31/2020 Green 01/31/2018 Green 01/31/2017 NA No Teamsters National Pipe Line Pension Plan 461102851 001 7.4 7.6 3.6 05/31/2020 Green 12/31/2017 (a) Green 12/31/2016 (a) NA No International Union of Operating Engineers Local 132 Pension Fund 556015364 001 5.6 2.3 0.2 05/31/2020 Green 03/31/2018 Green 03/31/2017 NA No West Virginia Laborers' Pension Trust Fund 556026775 001 4.5 3.0 0.5 05/31/2020 Green 03/31/2018 (a) Green 03/31/2017 NA No Laborers' National Pension Fund 751280827 001 4.1 3.5 3.0 05/31/2020 Red 12/31/2017 Green 12/31/2016 Implemented No Laborers' Pension Fund of Roanoke, Virginia 546111015 001 2.5 0.1 0.2 05/31/2020 Green 09/30/2017 Green 09/30/2016 (a) NA No IBEW Local 1249 Pension Plan 156035161 001 2.2 1.5 1.1 05/02/2021 Yellow 12/31/2017 Yellow 12/31/2016 Implemented No Ohio Operating Engineers Pension Plan 316129968 001 2.1 4.9 — 05/31/2020 Green 07/31/2017 Green 07/31/2016 NA No Laborers' Local Union No. 158 Pension Plan 236580323 001 1.5 1.8 0.4 04/30/2020 Green 12/31/2017 (a) Green 12/31/2016 NA No Employer - Teamsters Local Nos. 175 & 505 Pension Trust Fund 556021850 001 1.5 0.3 — 05/31/2020 Red 12/31/2017 (b) Red 12/31/2016 (b) Implemented No Michigan Laborers' Pension Plan 386233976 001 1.5 2.0 1.1 05/31/2020 Yellow 08/31/2018 Yellow 08/31/2017 (b) Implemented No National Electrical Benefit Fund 530181657 001 1.4 1.8 1.7 Varies through 5/31/2021 Green 12/31/2017 Green 12/31/2016 NA No Laborers' District Council of Western Pennsylvania Pension Fund 256135576 001 1.4 0.6 0.2 12/31/2020 Red 12/31/2017 Red 12/31/2016 Implemented No Operating Engineers' Local 324 Pension Fund 381900637 001 0.6 2.1 — 05/31/2020 Red 04/30/2018 Red 04/30/2017 Implemented No Other funds 15.0 (c) 10.2 (c) 12.7 (c) Total multiemployer pension plan contributions $ 92.4 $ 92.1 $ 59.9 (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 2018 , 2017 and 2016 contributions include approximately $0.2 million , $0.7 million and $0.9 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.

Equity (Tables)

Equity (Tables)	12 Months Ended
	Dec. 31, 2018
Accumulated Other Comprehensive Loss
Rollforward of Accumulated Other Comprehensive Loss	A rollforward of activity within accumulated other comprehensive income (loss) for the periods indicated was as follows (in thousands): For the Years Ended December 31, 2018 2017 2016 Foreign Currency Other Total Foreign Currency Other Total Foreign Currency Other Total Balance as of January 1 $ (62,851 ) $ (861 ) $ (63,712 ) $ (64,478 ) $ (1,336 ) $ (65,814 ) $ (67,063 ) $ (5,288 ) $ (72,351 ) Unrealized (losses) gains, net of tax (2,645 ) 5,863 3,218 1,627 475 2,102 2,585 3,952 6,537 Balance as of December 31 $ (65,496 ) $ 5,002 $ (60,494 ) $ (62,851 ) $ (861 ) $ (63,712 ) $ (64,478 ) $ (1,336 ) $ (65,814 )

Income Taxes (Tables)

Income Taxes (Tables)	12 Months Ended
	Dec. 31, 2018
Income Tax Disclosure [Abstract]
Schedule of Components of Income before Income Taxes	The components of income before income taxes for the periods indicated were as follows (in millions): For the Years Ended December 31, 2018 2017 2016 Domestic $ 341.1 $ 334.9 $ 202.4 Foreign 24.2 36.9 23.4 Total $ 365.3 $ 371.8 $ 225.8
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, 2018 2017 2016 Current: Federal $ 26.7 $ (6.0 ) $ 85.8 Foreign 9.4 11.5 3.0 State and local 10.5 (0.8 ) 6.7 $ 46.6 $ 4.7 $ 95.5 Deferred: Federal $ 43.9 $ 18.2 $ 6.1 Foreign 3.3 (7.5 ) (6.8 ) State and local 12.3 7.6 (3.0 ) $ 59.5 $ 18.3 $ (3.7 ) Provision for income taxes $ 106.1 $ 22.9 $ 91.8
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, 2018 2017 Deferred tax assets: Accrued insurance $ 25.9 $ 24.6 Operating loss carryforwards and tax credits 67.7 54.9 Compensation and benefits 15.2 7.5 Bad debt 2.4 1.2 Unrealized gains and losses — 11.4 Other 8.4 7.9 Valuation allowance (40.6 ) (40.5 ) Total deferred tax assets $ 79.0 $ 67.0 Deferred tax liabilities: Property and equipment $ 146.3 $ 104.1 Goodwill 55.6 56.7 Other intangible assets 28.1 28.7 Gain on remeasurement of equity investee 7.1 6.9 Revenue recognition 21.6 11.3 Investments in unconsolidated entities 67.9 52.8 Other 16.1 11.0 Total deferred tax liabilities $ 342.7 $ 271.5 Net deferred tax liabilities $ (263.7 ) $ (204.5 )
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, 2018 2017 2016 U.S. statutory federal rate applied to pretax income 21.0 % 35.0 % 35.0 % State and local income taxes, net of federal benefit 4.2 2.0 2.6 Foreign tax rate differential 1.5 0.3 (0.1 ) Non-deductible expenses 1.7 2.2 4.4 Goodwill and intangible assets 3.6 (0.0 ) (0.7 ) Change in tax rate (2.8 ) (32.3 ) (1.9 ) Domestic production activities deduction 0.0 (0.2 ) (2.9 ) Other (2.4 ) (0.7 ) (0.1 ) Tax credits (0.4 ) (2.8 ) (0.0 ) Valuation allowance for deferred tax assets 2.6 2.7 4.3 Effective income tax rate 29.0 % 6.2 % 40.6 %
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, 2018 2017 2016 Beginning balance $ 8.1 $ — $ — Additions based on tax positions related to the current year 2.7 3.2 — Additions for tax positions of prior years — 4.9 — Reductions for tax positions of prior years (1.4 ) — — Ending balance $ 9.4 $ 8.1 $ —

Segments and Related Informat_2

Segments and Related Information (Tables)	12 Months Ended
	Dec. 31, 2018
Segment Reporting [Abstract]
Schedule of Financial Information by Reportable Segment	Summarized financial information for MasTec’s reportable segments is presented and reconciled to consolidated financial information for total MasTec in the following tables, including a reconciliation of consolidated income before income taxes to EBITDA, all of which are presented in millions. The tables below may contain slight summation differences due to rounding. For the Years Ended December 31, Revenue: 2018 2017 2016 Communications (a) $ 2,556.8 $ 2,424.4 $ 2,323.6 Oil and Gas 3,288.7 3,497.2 2,024.4 Electrical Transmission 397.3 378.2 383.8 Power Generation and Industrial 665.0 299.9 405.7 Other 3.5 20.8 15.9 Eliminations (1.9 ) (13.5 ) (18.7 ) Consolidated revenue $ 6,909.4 $ 6,607.0 $ 5,134.7 (a) Revenue generated primarily by utilities customers represented 14.9% , 13.4% and 11.1% of Communications segment revenue for the years ended December 31, 2018 , 2017 and 2016 , respectively. For the Years Ended December 31, EBITDA: 2018 2017 2016 Communications $ 290.4 $ 247.4 $ 244.6 Oil and Gas 451.6 402.2 297.3 Electrical Transmission 10.5 17.6 (42.9 ) Power Generation and Industrial 40.4 22.6 18.3 Other 24.4 19.8 (2.6 ) Corporate (156.4 ) (88.7 ) (73.1 ) Consolidated EBITDA $ 660.8 $ 620.9 $ 441.5 For the Years Ended December 31, Depreciation and Amortization: 2018 2017 2016 Communications $ 59.3 $ 53.2 $ 50.3 Oil and Gas 113.7 96.7 78.4 Electrical Transmission 19.8 22.8 23.2 Power Generation and Industrial 13.7 9.1 6.2 Other 0.1 0.1 0.1 Corporate 6.3 6.1 6.7 Consolidated depreciation and amortization $ 212.9 $ 188.0 $ 164.9 As of December 31, Assets: 2018 2017 2016 Communications $ 1,461.7 $ 1,314.4 $ 1,156.9 Oil and Gas 1,965.3 1,762.6 1,267.2 Electrical Transmission 423.9 471.4 419.1 Power Generation and Industrial 358.7 288.6 268.1 Other 193.9 153.2 27.7 Corporate 36.5 76.4 44.1 Consolidated segment assets $ 4,440.0 $ 4,066.6 $ 3,183.1 For the Years Ended December 31, Capital Expenditures: 2018 2017 2016 Communications $ 69.3 $ 40.5 $ 28.5 Oil and Gas 83.5 57.7 64.0 Electrical Transmission 10.2 14.9 19.8 Power Generation and Industrial 6.5 5.4 3.4 Other 0.0 0.0 0.3 Corporate 10.9 4.9 1.1 Consolidated capital expenditures $ 180.4 $ 123.4 $ 117.1
Reconciliation of Consolidated Income before Income Taxes to EBITDA	For the Years Ended December 31, EBITDA Reconciliation: 2018 2017 2016 Income before income taxes $ 365.3 $ 371.8 $ 225.8 Plus: Interest expense, net 82.6 61.0 50.7 Depreciation and amortization 212.9 188.0 164.9 Consolidated EBITDA $ 660.8 $ 620.9 $ 441.5
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, 2018 2017 2016 Customer: AT&T (including DIRECTV ® ) (a) 23% 25% 34% EQT Corporation (b) 20% —% —% Energy Transfer affiliates (c) 14% 40% 27% (a) 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. (b) The Company's relationship with EQT Corporation and its affiliates is based upon various construction contracts for pipeline activities. Revenue from EQT Corporation is included in the Oil and Gas segment. (c) 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.

Quarterly Information (Unaudi_2

Quarterly Information (Unaudited) (Tables)	12 Months Ended
	Dec. 31, 2018
Quarterly Financial Information Disclosure [Abstract]
Schedule of Quarterly Information (Unaudited)	The following table presents selected unaudited quarterly operating results for the years ended December 31, 2018 and 2017 (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 2018 Quarters Ended For the 2017 Quarters Ended March 31 June 30 September 30 December 31 March 31 June 30 September 30 December 31 Revenue $ 1,396.8 $ 1,617.8 $ 1,977.2 $ 1,917.6 $ 1,158.2 $ 1,890.2 $ 1,955.8 $ 1,602.9 Costs of revenue, excluding depreciation and amortization $ 1,237.3 $ 1,366.6 $ 1,681.4 $ 1,654.0 $ 971.1 $ 1,626.3 $ 1,726.2 $ 1,421.7 Net income $ 26.5 $ 80.4 $ 120.5 $ 31.8 $ 40.6 $ 83.3 $ 64.2 $ 160.7 Net income attributable to MasTec, Inc. $ 26.6 $ 80.5 $ 120.7 $ 31.9 $ 41.0 $ 81.7 $ 63.8 $ 160.8 Earnings per share: Basic $ 0.33 $ 1.02 $ 1.55 $ 0.42 $ 0.51 $ 1.01 $ 0.79 $ 1.98 Diluted $ 0.32 $ 1.01 $ 1.52 $ 0.41 $ 0.50 $ 0.99 $ 0.77 $ 1.95

Supplemental Guarantor Financ_2

Supplemental Guarantor Financial Information (Tables)	12 Months Ended
	Dec. 31, 2018
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, 2018 MasTec, Inc. Guarantor Subsidiaries Non-Guarantor Subsidiaries Eliminations Consolidated MasTec, Inc. Revenue $ — $ 6,539.3 $ 492.6 $ (122.5 ) $ 6,909.4 Costs of revenue, excluding depreciation and amortization — 5,609.4 452.4 (122.5 ) 5,939.3 Depreciation and amortization — 190.5 22.4 — 212.9 Goodwill impairment — — 47.7 — 47.7 General and administrative expenses 3.1 266.4 17.8 — 287.3 Interest expense (income), net — 147.0 (64.4 ) — 82.6 Equity in earnings of unconsolidated affiliates — — (23.9 ) — (23.9 ) Other expense (income), net — 2.9 (4.7 ) — (1.8 ) (Loss) income before income taxes $ (3.1 ) $ 323.1 $ 45.3 $ — $ 365.3 Benefit from (provision for) income taxes 0.9 (94.2 ) (12.8 ) — (106.1 ) Net (loss) income before equity in income from subsidiaries $ (2.2 ) $ 228.9 $ 32.5 $ — $ 259.2 Equity in income from subsidiaries, net of tax 261.9 — — (261.9 ) — Net income (loss) $ 259.7 $ 228.9 $ 32.5 $ (261.9 ) $ 259.2 Net loss attributable to non-controlling interests — — (0.4 ) — (0.4 ) Net income (loss) attributable to MasTec, Inc. $ 259.7 $ 228.9 $ 32.9 $ (261.9 ) $ 259.7 Comprehensive income (loss) $ 262.9 $ 228.9 $ 35.7 $ (265.1 ) $ 262.4 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 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
Condensed Consolidating Balance Sheets	CONDENSED CONSOLIDATING BALANCE SHEETS (in millions) As of December 31, 2018 MasTec, Inc. Guarantor Subsidiaries Non-Guarantor Subsidiaries Eliminations Consolidated MasTec, Inc. Assets Total current assets $ — $ 1,993.0 $ 248.5 $ (72.5 ) $ 2,169.0 Property and equipment, net — 699.2 48.6 — 747.8 Goodwill and other intangible assets, net — 1,188.0 81.7 — 1,269.7 Investments in and advances to consolidated affiliates, net 1,373.1 1,138.4 816.9 (3,328.4 ) — Other long-term assets 16.8 42.0 194.6 — 253.4 Total assets $ 1,389.9 $ 5,060.6 $ 1,390.3 $ (3,400.9 ) $ 4,440.0 Liabilities and equity Total current liabilities $ — $ 1,185.9 $ 170.2 $ (72.5 ) $ 1,283.6 Long-term debt — 1,319.4 4.9 — 1,324.2 Other long-term liabilities — 429.2 10.8 — 440.1 Total liabilities $ — $ 2,934.5 $ 185.9 $ (72.5 ) $ 3,047.9 Total equity $ 1,389.9 $ 2,126.1 $ 1,204.4 $ (3,328.4 ) $ 1,392.0 Total liabilities and equity $ 1,389.9 $ 5,060.6 $ 1,390.3 $ (3,400.9 ) $ 4,440.0 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
Condensed Consolidating Statements of Cash Flows	CONDENSED CONSOLIDATING STATEMENTS OF CASH FLOWS (in millions) For the Year Ended December 31, 2018 MasTec, Inc. Guarantor Subsidiaries Non-Guarantor Subsidiaries Eliminations Consolidated MasTec, Inc. Net cash provided by operating activities $ — $ 341.6 $ 188.4 $ — $ 530.0 Cash flows from investing activities: Cash paid for acquisitions, net of cash acquired — (6.7 ) — — (6.7 ) Capital expenditures — (174.3 ) (6.1 ) — (180.4 ) Proceeds from sale of property and equipment — 26.2 13.1 — 39.4 Payments for other investments — (11.8 ) (27.6 ) — (39.5 ) Proceeds from other investments — — 5.4 — 5.4 Net cash used in investing activities $ — $ (166.6 ) $ (15.2 ) $ — $ (181.8 ) Cash flows from financing activities: Proceeds from credit facilities — 3,383.9 34.3 — 3,418.2 Repayments of credit facilities — (3,314.8 ) (44.7 ) — (3,359.5 ) Repayments of other borrowings and capital lease obligations, net — (83.7 ) (5.9 ) — (89.6 ) Payments of acquisition-related contingent consideration — (15.9 ) — — (15.9 ) Payments to non-controlling interests, including acquisition of interests and distributions — (0.6 ) — — (0.6 ) Proceeds from stock-based awards, net 0.2 — — — 0.2 Repurchase of common stock (313.9 ) — — — (313.9 ) Other financing activities, net — — — — — Net financing activities and advances from (to) consolidated affiliates 313.7 (142.1 ) (171.6 ) — — Net cash used in financing activities $ — $ (173.2 ) $ (187.9 ) $ — $ (361.1 ) Effect of currency translation on cash — — — — — Net increase (decrease) in cash and cash equivalents $ — $ 1.8 $ (14.7 ) $ — $ (12.9 ) Cash and cash equivalents - beginning of period — 10.1 30.3 — 40.3 Cash and cash equivalents - end of period $ — $ 11.9 $ 15.6 $ — $ 27.4 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 $ — $ 142.9 $ 1.2 $ — $ 144.1 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 — (6.6 ) — — (6.7 ) 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 $ — $ 58.8 $ 71.5 $ — $ 130.3 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 CONDENSED CONSOLIDATING STATEMENTS OF CASH FLOWS (in millions) 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

Business, Basis of Presentati_3

Business, Basis of Presentation and Significant Accounting Policies (Narrative) (Details) $ in Thousands	12 Months Ended
	Dec. 31, 2018USD ($)segment	Dec. 31, 2017USD ($)	Dec. 31, 2016USD ($)	Dec. 31, 2015USD ($)
Business, Basis Of Presentation And Significant Accounting Policies [Line Items]
Number of reportable segments | segment	5
Valuation allowances for inventory	$ 7,800	$ 7,700
Cash	27,422	40,326	$ 38,767	$ 4,984
Financing costs incurred		6,300
Amortization of deferred financing costs	2,900	3,300	$ 3,200
Deferred financing costs, net of accumulated amortization	10,100	13,000
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] | Automobile Liability [Member]
Business, Basis Of Presentation And Significant Accounting Policies [Line Items]
Per claim deductible, insurance policies	3,000
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
Proportionately Consolidated Non-Controlled Joint Venture [Member]
Business, Basis Of Presentation And Significant Accounting Policies [Line Items]
Cash	$ 11,800	$ 17,300

Business, Basis of Presentati_4

Business, Basis of Presentation and Significant Accounting Policies (Revenue Recognition) (Narrative) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016	Jan. 01, 2018
Revenue [Line Items]
Retained earnings, cumulative effect recognized on intial application of the new guidance (in dollars)	$ 1,118,375	$ 857,154
Revenue recognition, performance obligations satisfied in previous periods, revenue recognized (in dollars)	38,500
Contract with customer, unapproved change orders and/or claims, amount (in dollars)	$ 56,000	$ 146,000
Maximum [Member]
Revenue [Line Items]
Revenue recognition, changes In contract estimates, cost-to-cost method, financial effect, percentage	5.00%	5.00%
Change order or claim approval process, term within which expected to be completed (in years)	1 year
Maximum [Member] | Plan [Member]
Revenue [Line Items]
Revenue recognition, performance obligations, completion period (in years)	1 year
Revenue [Member] | Concentration Risk from Type of Arrangement [Member] | Master Service and Other Service Agreements [Member]
Revenue [Line Items]
Concentration risk, percentage of total	35.00%	36.00%	43.00%
Revenue [Member] | Concentration Risk from Type of Arrangement [Member] | Master Service and Other Service Agreements [Member] | Point in Time [Member]
Revenue [Line Items]
Concentration risk, percentage of total	7.00%
ASU 2014-09 [Member] | Difference between Revenue Guidance in Effect before and after Topic 606 [Member]
Revenue [Line Items]
Retained earnings, cumulative effect recognized on intial application of the new guidance (in dollars)				$ 2,000

Business, Basis of Presentati_5

Business, Basis of Presentation and Significant Accounting Policies (Remaining Performance Obligations) (Narrative) (Details) $ in Billions	Dec. 31, 2018USD ($)
Revenue from Contract with Customer [Abstract]
Revenue recognition, remaining performance obligations, contract price allocated (in dollars)	$ 5
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2019-01-01
Revenue from Contract with Customer [Abstract]
Revenue recognition, remaining performance obligations, contract price allocated (in dollars)	$ 4.3
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Revenue recognition, remaining performance obligations, completion period (in months)	12 months

Business, Basis of Presentati_6

Business, Basis of Presentation and Significant Accounting Policies (Goodwill and Indefinite-Lived Intangible Assets) (Narrative) (Details) $ in Thousands	3 Months Ended	12 Months Ended
	Dec. 31, 2018USD ($)yr	Dec. 31, 2018USD ($)yrcomponentreportingunit	Dec. 31, 2017USD ($)yrcomponentreportingunit	Dec. 31, 2016USD ($)yrcomponentreportingunit
Goodwill and Indefinite-Lived Intangible Assets [Line Items]
Goodwill, pre-tax impairment charge (in dollars)	$ 47,700	$ 47,662	$ 0	$ 0
Goodwill, carrying amount (in dollars)	1,100,350	1,100,350	1,137,738	995,900
Pre-Qualifications [Member]
Goodwill and Indefinite-Lived Intangible Assets [Line Items]
Indefinite-lived intangible assets, carrying amount (in dollars)	74,000	74,000	77,600	74,600
Trade Names [Member]
Goodwill and Indefinite-Lived Intangible Assets [Line Items]
Indefinite-lived intangible assets, carrying amount (in dollars)	$ 34,500	$ 34,500	$ 34,500	$ 34,500
Goodwill [Member] | Reporting Unit Or Intangible, Quantitative Testing [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%
Terminal Growth Rate [Member]
Goodwill and Indefinite-Lived Intangible Assets [Line Items]
Goodwill impairment testing, measurement input			0.035
Terminal Growth Rate [Member] | Minimum [Member]
Goodwill and Indefinite-Lived Intangible Assets [Line Items]
Goodwill impairment testing, measurement input	0.024	0.024		0.030
Terminal Growth Rate [Member] | Maximum [Member]
Goodwill and Indefinite-Lived Intangible Assets [Line Items]
Goodwill impairment testing, measurement input	0.035	0.035		0.035
Number of Years of Discounted Cash Flows [Member]
Goodwill and Indefinite-Lived Intangible Assets [Line Items]
Goodwill impairment testing, measurement input | yr				9
Number of Years of Discounted Cash Flows [Member] | Minimum [Member]
Goodwill and Indefinite-Lived Intangible Assets [Line Items]
Goodwill impairment testing, measurement input | yr	4	4	5
Number of Years of Discounted Cash Flows [Member] | Minimum [Member] | Pre-Qualifications [Member]
Goodwill and Indefinite-Lived Intangible Assets [Line Items]
Indefinite-lived intangible assets, impairment testing, measurement input | yr	2	2	2	2
Number of Years of Discounted Cash Flows [Member] | Maximum [Member]
Goodwill and Indefinite-Lived Intangible Assets [Line Items]
Goodwill impairment testing, measurement input | yr	9	9	9
Number of Years of Discounted Cash Flows [Member] | Maximum [Member] | Pre-Qualifications [Member]
Goodwill and Indefinite-Lived Intangible Assets [Line Items]
Indefinite-lived intangible assets, impairment testing, measurement input | yr	4	4	4	3
Discount Rate [Member] | Minimum [Member]
Goodwill and Indefinite-Lived Intangible Assets [Line Items]
Goodwill impairment testing, measurement input	0.110	0.110	0.130	0.130
Discount Rate [Member] | Minimum [Member] | Pre-Qualifications [Member]
Goodwill and Indefinite-Lived Intangible Assets [Line Items]
Indefinite-lived intangible assets, impairment testing, measurement input	0.130	0.130	0.130	0.130
Discount Rate [Member] | Maximum [Member]
Goodwill and Indefinite-Lived Intangible Assets [Line Items]
Goodwill impairment testing, measurement input	0.160	0.160	0.155	0.145
Discount Rate [Member] | Maximum [Member] | Pre-Qualifications [Member]
Goodwill and Indefinite-Lived Intangible Assets [Line Items]
Indefinite-lived intangible assets, impairment testing, measurement input	0.140	0.140	0.140	0.135
Power Generation and Industrial [Member]
Goodwill and Indefinite-Lived Intangible Assets [Line Items]
Number of aggregated components in reporting unit | component		2	2	1
Goodwill impairment testing, number of reporting units | reportingunit			1
Goodwill, pre-tax impairment charge (in dollars)		$ 0
Goodwill, carrying amount (in dollars)	$ 143,100	$ 143,100	$ 135,800	$ 117,600
Power Generation and Industrial [Member] | Number of Years of Discounted Cash Flows [Member] | Trade Names [Member]
Goodwill and Indefinite-Lived Intangible Assets [Line Items]
Indefinite-lived intangible assets, impairment testing, measurement input | yr			5
Power Generation and Industrial [Member] | Discount Rate [Member] | Trade Names [Member]
Goodwill and Indefinite-Lived Intangible Assets [Line Items]
Indefinite-lived intangible assets, impairment testing, measurement input			0.14
Communications [Member]
Goodwill and Indefinite-Lived Intangible Assets [Line Items]
Number of aggregated components in reporting unit | component		1	1	1
Goodwill impairment testing, number of reporting units | reportingunit		2
Goodwill, pre-tax impairment charge (in dollars)		$ 0
Goodwill, carrying amount (in dollars)	467,800	$ 467,800	$ 466,400	$ 420,700
Oil and Gas [Member]
Goodwill and Indefinite-Lived Intangible Assets [Line Items]
Number of aggregated components in reporting unit | component		1	1	1
Goodwill impairment testing, number of reporting units | reportingunit		3	2	2
Goodwill, pre-tax impairment charge (in dollars)		$ 47,700
Goodwill, carrying amount (in dollars)	339,600	$ 339,600	$ 385,600	$ 307,700
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 | reportingunit		1
Goodwill, carrying amount (in dollars)	14,000	$ 14,000
Oil and Gas [Member] | Reporting Unit Or Intangible, Quantitative Testing [Member]
Goodwill and Indefinite-Lived Intangible Assets [Line Items]
Goodwill impairment testing, number of reporting units | reportingunit			2	1
Goodwill, carrying amount (in dollars)	$ 15,000	$ 15,000		$ 15,000
Goodwill impairment testing, reporting unit, percentage of estimated fair value in excess of carrying value	5.00%	5.00%		11.00%
Oil and Gas [Member] | Reporting Unit Or Intangible, Quantitative Testing [Member] | Pre-Qualifications [Member]
Goodwill and Indefinite-Lived Intangible Assets [Line Items]
Indefinite-lived intangible assets, carrying amount (in dollars)	$ 43,000	$ 43,000	$ 45,000
Indefinite-lived intangible assets impairment testing, percentage of estimated fair value in excess of carrying value	16.00%	16.00%	19.00%
Oil and Gas [Member] | Reporting Unit A, Quantitative Testing [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 [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] | Goodwill [Member] | Reporting Unit Or Intangible, Quantitative Testing [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%
Oil and Gas [Member] | Indefinite-lived Intangible Assets [Member] | Reporting Unit Or Intangible, Quantitative Testing [Member] | Pre-Qualifications [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%
Electrical Transmission [Member]
Goodwill and Indefinite-Lived Intangible Assets [Line Items]
Percentage of aggregated components in reporting unit		100.00%	100.00%	100.00%
Goodwill, pre-tax impairment charge (in dollars)		$ 0
Goodwill, carrying amount (in dollars)	$ 149,900	$ 149,900	$ 149,900	$ 149,900
Goodwill impairment testing, reporting unit, percentage of estimated fair value in excess of carrying value				5.00%
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%
Other [Member]
Goodwill and Indefinite-Lived Intangible Assets [Line Items]
Number of aggregated components in reporting unit | component		1	1	1

Business, Basis of Presentati_7

Business, Basis of Presentation and Significant Accounting Policies (Stock-Based Compensation) (Narrative) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock-based compensation, shares withheld (in shares)	96,739	138,519	44,988
Stock-based compensation, payments for employee tax obligations to taxing authorities (in dollars)	$ 3.8	$ 6.2	$ 0.6
Restricted Shares [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 plans, description	The Company has certain employee stock purchase plans (collectively, “ESPPs”) under which shares of the Company’s common stock are available for purchase by eligible participants. These plans allow participants 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.
Stock-based compensation, fair value assumptions, expected dividend yield (percentage)	0.00%

Business, Basis of Presentati_8

Business, Basis of Presentation and Significant Accounting Policies (Restructuring Activities) (Narrative) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2018	Dec. 31, 2017
Restructuring Activities [Line Items]
Restructuring liabilities, current		$ 1.5	$ 2.2
General and Administrative Expense [Member]
Restructuring Activities [Line Items]
Restructuring charges (in dollars)	$ 12.3
Other Expense [Member]
Restructuring Activities [Line Items]
Restructuring charges (in dollars)	$ 2.9

Business, Basis of Presentati_9

Business, Basis of Presentation and Significant Accounting Policies (New Accounting Pronouncements) (Narrative) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Jan. 01, 2019
ASU 2016-15 [Member]
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Payments for contingent consideration liabilities, operating activities, reclassification adjustment (in dollars)	$ 12
Forecast [Member] | Minimum [Member] | ASU 2016-02 [Member]
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Operating leases, right-of-use assets		$ 200
Operating leases, liabilities		200
Forecast [Member] | Maximum [Member] | ASU 2016-02 [Member]
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Operating leases, right-of-use assets		230
Operating leases, liabilities		$ 230

Earnings Per Share (Narrative)

Earnings Per Share (Narrative) (Details) - shares	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Earnings Per Share [Line Items]
Computation of earnings per share, methodology		Basic earnings or loss per share is computed by dividing net income 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 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.
Effect of share repurchases, decrease in weighted average shares outstanding (in shares)		2,800,000
Forecast [Member]
Earnings Per Share [Line Items]
Effect of share repurchases, decrease in weighted average shares outstanding (in shares)	4,400,000
Treasury Stock, Common [Member]
Earnings Per Share [Line Items]
Treasury stock acquired (in shares)		7,197,006	38,807	0

Earnings Per Share (Schedule of

Earnings Per Share (Schedule of Earnings Per Share Information) (Details) - USD ($) shares in Thousands, $ in Thousands		3 Months Ended								12 Months Ended
		Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2018		Dec. 31, 2017		Dec. 31, 2016
Net income attributable to MasTec:
Net income - basic (in dollars)		$ 31,900	$ 120,700	$ 80,500	$ 26,600	$ 160,800	$ 63,800	$ 81,700	$ 41,000	$ 259,659	[1]	$ 347,213	[1]	$ 131,263	[1]
Net income - diluted (in dollars)	[1]									$ 259,659		$ 347,213		$ 131,263
Weighted average shares outstanding:
Weighted average shares outstanding - basic										78,695		80,903		80,372
Dilutive common stock equivalents (in shares)										1,077		1,422		1,022
Weighted average shares outstanding - diluted										79,772		82,325		81,394
[1]	Calculated as total net income less amounts attributable to non-controlling interests.

Goodwill and Other Intangible_3

Goodwill and Other Intangible Assets (Narrative) (Details) - USD ($) $ in Thousands	3 Months Ended	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Goodwill and Intangible Assets Disclosure [Abstract]
Goodwill, pre-tax impairment charge (in dollars)	$ 47,700	$ 47,662	$ 0	$ 0
Amortization expense, intangible assets		$ 20,600	$ 20,900	$ 21,300

Goodwill and Other Intangible_4

Goodwill and Other Intangible Assets (Rollforward of Goodwill by Segment) (Details) - USD ($) $ in Thousands		3 Months Ended	12 Months Ended
		Dec. 31, 2018	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2018	Dec. 31, 2016
Goodwill [Line Items]
Goodwill, gross						$ 1,216,400	$ 1,065,800
Goodwill, accumulated impairment loss	[1]					(116,000)	(69,900)
Goodwill, net		$ 1,100,350	$ 1,137,738	$ 995,900	$ 995,900	1,100,350	995,900
Goodwill [Roll Forward]
Goodwill, net, beginning balance			1,137,738	995,900
Additions from new business combinations			9,800	138,000
Measurement period adjustments, net	[2]		4,600
Goodwill impairment		(47,700)	(47,662)	0	0
Currency translation adjustments			(4,000)	3,800
Goodwill, net, ending balance		1,100,350	1,100,350	1,137,738	995,900
Communications [Member]
Goodwill [Line Items]
Goodwill, gross						467,800	420,700
Goodwill, accumulated impairment loss	[1]					0	0
Goodwill, net		467,800	466,400	420,700	420,700	467,800	420,700
Goodwill [Roll Forward]
Goodwill, net, beginning balance			466,400	420,700
Additions from new business combinations			0	45,700
Measurement period adjustments, net	[2]		1,400
Goodwill impairment			0
Currency translation adjustments			0	0
Goodwill, net, ending balance		467,800	467,800	466,400	420,700
Oil and Gas [Member]
Goodwill [Line Items]
Goodwill, gross						455,600	377,600
Goodwill, accumulated impairment loss	[1]					(116,000)	(69,900)
Goodwill, net		339,600	385,600	307,700	307,700	339,600	307,700
Goodwill [Roll Forward]
Goodwill, net, beginning balance			385,600	307,700
Additions from new business combinations			0	74,100
Measurement period adjustments, net	[2]		5,700
Goodwill impairment			(47,700)
Currency translation adjustments			(4,000)	3,800
Goodwill, net, ending balance		339,600	339,600	385,600	307,700
Electrical Transmission [Member]
Goodwill [Line Items]
Goodwill, gross						149,900	149,900
Goodwill, accumulated impairment loss	[1]					0	0
Goodwill, net		149,900	149,900	149,900	149,900	149,900	149,900
Goodwill [Roll Forward]
Goodwill, net, beginning balance			149,900	149,900
Additions from new business combinations			0	0
Measurement period adjustments, net	[2]		0
Goodwill impairment			0
Currency translation adjustments			0	0
Goodwill, net, ending balance		149,900	149,900	149,900	149,900
Power Generation and Industrial [Member]
Goodwill [Line Items]
Goodwill, gross						143,100	117,600
Goodwill, accumulated impairment loss	[1]					0	0
Goodwill, net		143,100	135,800	117,600	117,600	$ 143,100	$ 117,600
Goodwill [Roll Forward]
Goodwill, net, beginning balance			135,800	117,600
Additions from new business combinations			9,800	18,200
Measurement period adjustments, net	[2]		(2,500)
Goodwill impairment			0
Currency translation adjustments			0	0
Goodwill, net, ending balance		$ 143,100	$ 143,100	$ 135,800	$ 117,600
[1]	Accumulated impairment losses include the effects of currency translation gains and/or losses.
[2]	Represents adjustments to preliminary estimates of fair value within the measurement period of up to one year from the date of acquisition.

Goodwill and Other Intangible_5

Goodwill and Other Intangible Assets (Rollforward of Other Intangible Assets) (Details) - USD ($) $ in Thousands		Dec. 31, 2018	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2016
Other Intangible Assets [Line Items]
Other intangible assets, gross						$ 323,300
Accumulated amortization						(143,600)
Other Intangible Assets [Roll Forward]
Other intangible assets, net, beginning balance			$ 191,142	$ 179,700
Additions from new business combinations			3,600	28,800
Measurement period adjustments	[1]		(700)
Amortization expense			(20,600)	(20,900)	$ (21,300)
Currency translation adjustments			(4,000)	3,500
Other intangible assets, net, amortizing, ending balance		$ 60,900	60,900
Other intangible assets, net, ending balance		$ 169,370	169,370	191,142	179,700
Weighted Average [Member]
Other Intangible Assets [Roll Forward]
Remaining weighted average amortization period (in years)		8 years
Customer Relationships and Backlog [Member]
Other Intangible Assets [Line Items]
Other intangible assets, amortizing, gross						195,100
Accumulated amortization						(131,900)
Other Intangible Assets [Roll Forward]
Other intangible assets, net, amortizing, beginning balance			70,600	63,200
Additions from new business combinations, amortizing intangible assets			3,300	26,300
Measurement period adjustments, amortizing intangible assets	[1]		0
Amortization expense			(19,200)	(19,300)
Currency translation adjustments, amortizing intangible assets			(300)	400
Other intangible assets, net, amortizing, ending balance		$ 54,400	54,400	70,600	63,200
Customer Relationships and Backlog [Member] | Weighted Average [Member]
Other Intangible Assets [Roll Forward]
Remaining weighted average amortization period (in years)		8 years
Other Amortizing Intangible Assets [Member]
Other Intangible Assets [Line Items]
Other intangible assets, amortizing, gross	[2]					19,100
Accumulated amortization	[2]					(11,700)
Other Intangible Assets [Roll Forward]
Other intangible assets, net, amortizing, beginning balance	[2]		8,400	7,400
Additions from new business combinations, amortizing intangible assets	[2]		300	2,500
Measurement period adjustments, amortizing intangible assets	[1],[2]		(700)
Amortization expense	[2]		(1,400)	(1,600)
Currency translation adjustments, amortizing intangible assets	[2]		(100)	100
Other intangible assets, net, amortizing, ending balance	[2]	$ 6,500	6,500	8,400	7,400
Other Amortizing Intangible Assets [Member] | Weighted Average [Member]
Other Intangible Assets [Roll Forward]
Remaining weighted average amortization period (in years)	[2]	7 years
Trade Names [Member]
Other Intangible Assets [Line Items]
Other intangible assets, non-amortizing		$ 34,500	34,500	34,500	34,500	34,500
Other Intangible Assets [Roll Forward]
Other intangible assets, non-amortizing, beginning balance			34,500	34,500
Additions from new business combinations, non-amortizing intangible assets			0	0
Measurement period adjustments, non-amortizing intangible assets	[1]		0
Currency translation adjustments, non-amortizing intangible assets			0	0
Other intangible assets, non-amortizing, ending balance		34,500	34,500	34,500	34,500
Pre-Qualifications [Member]
Other Intangible Assets [Line Items]
Other intangible assets, non-amortizing		74,000	77,600	74,600	74,600	$ 74,600
Other Intangible Assets [Roll Forward]
Other intangible assets, non-amortizing, beginning balance			77,600	74,600
Additions from new business combinations, non-amortizing intangible assets			0	0
Measurement period adjustments, non-amortizing intangible assets	[1]		0
Currency translation adjustments, non-amortizing intangible assets			(3,600)	3,000
Other intangible assets, non-amortizing, ending balance		$ 74,000	$ 74,000	$ 77,600	$ 74,600
[1]	Represents adjustments to preliminary estimates of fair value within the measurement period of up to one year from the date of acquisition.
[2]	Consists principally of trade names and non-compete agreements.

Goodwill and Other Intangible_6

Goodwill and Other Intangible Assets (Schedule of Expected Future Amortization Expense) (Details) $ in Millions	Dec. 31, 2018USD ($)
Amortization Expense
Intangible assets, expected future amortization expense, 2019	$ 14.6
Intangible assets, expected future amortization expense, 2020	11.2
Intangible assets, expected future amortization expense, 2021	8.5
Intangible assets, expected future amortization expense, 2022	6.9
Intangible assets, expected future amortization expense, 2023	4.9
Intangible assets, expected future amortization expense, thereafter	14.8
Intangible assets, expected future amortization expense, total	$ 60.9

Goodwill and Other Intangible_7

Goodwill and Other Intangible Assets (2018 Acquisitions) (Narrative) (Details) - USD ($) $ in Millions	3 Months Ended	12 Months Ended
	Mar. 31, 2018	Dec. 31, 2018
Business Combinations [Line Items]
Business combinations, contingent consideration liabilities, range of potential undiscounted earn-out liabilities, high (in dollars)		$ 157
Business combinations, contingent consideration liabilities, range of potential earn-out liabilities, maximum unlimited		there is no maximum payment amount
2018 Acquisitions [Member]
Business Combinations [Line Items]
Business combinations, cash paid (in dollars)	$ 6.8
Contingent consideration, earn-out liability		$ 1.5
Business combinations, contingent consideration liabilities, range of potential undiscounted earn-out liabilities, high (in dollars)		$ 7
Business combinations, contingent consideration liabilities, range of potential earn-out liabilities, maximum unlimited		there is no maximum payment amount
Construction Management Firm Specializing in Steel Building Systems [Member]
Business Combinations [Line Items]
Business combinations, percentage of interests acquired		100.00%

Goodwill and Other Intangible_8

Goodwill and Other Intangible Assets (2017 Acquisitions) (Narrative) (Details) $ in Millions	12 Months Ended
	Dec. 31, 2018USD ($)yr	Dec. 31, 2017acquisition
Business Combinations [Line Items]
Business combinations, number of acquisitions | acquisition		3
Business combinations, contingent consideration liabilities, range of potential undiscounted earn-out liabilities, low (in dollars)	$ 30
Business combinations, contingent consideration liabilities, range of potential undiscounted earn-out liabilities, high (in dollars)	$ 157
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%
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’s 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)	$ 94
Business combinations, contingent consideration, basis for amount	The contingent consideration (earn-out liability) included in the table above equals a portion of the acquired companies’ earnings before interest, taxes, depreciation and amortization (“EBITDA”) in excess of thresholds agreed upon with the sellers, if applicable. Earn-outs are generally payable annually for a period of five years, as set forth in the respective purchase agreements.
Business combinations, contingent consideration liabilities, range of potential undiscounted earn-out liabilities, low (in dollars)	$ 24
Business combinations, contingent consideration liabilities, range of potential undiscounted earn-out liabilities, high (in dollars)	$ 145
Business combinations, contingent consideration liabilities, range of potential earn-out liabilities, maximum unlimited	there is no maximum payment amount
2017 Acquisitions [Member] | Expected Term [Member]
Business Combinations [Line Items]
Business combinations, contingent consideration, earn-out period (in years) | yr	5
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)		6 years

Goodwill and Other Intangible_9

Goodwill and Other Intangible Assets (Schedule of Consideration Paid and Net Assets Acquired, Business Combinations, 2017 Acquisitions) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Acquisition consideration:
Estimated fair value of contingent consideration (earn-out liability)	$ 6,461	$ 102,534	$ 0
Identifiable assets acquired and liabilities assumed:
Goodwill	$ 1,100,350	1,137,738	$ 995,900
2017 Acquisitions [Member]
Acquisition consideration:
Cash		120,400
Estimated fair value of contingent consideration (earn-out liability)		98,500
Total consideration transferred		218,900
Identifiable assets acquired and liabilities assumed:
Current assets, primarily composed of accounts receivable and $2.8 million of cash acquired		43,800
Cash acquired		2,800
Property and equipment and other long-term assets		57,200
Amortizing intangible assets		28,100
Current liabilities, including current portion of capital lease obligations and long-term debt		(29,500)
Long-term debt, including capital lease obligations		(9,900)
Deferred income taxes and other long-term liabilities		(12,000)
Total identifiable net assets		77,700
Goodwill		141,200
Total net assets acquired, including goodwill		$ 218,900

Goodwill and Other Intangibl_10

Goodwill and Other Intangible Assets (Pro Forma Financial Information and Acquisition Results) (Narrative) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017
Business Combinations [Abstract]
Business combinations, unaudited supplemental pro forma revenue	$ 6,912.5	$ 6,724.8
Business combinations, unaudited supplemental pro forma net income	$ 257.7	351.3
Business combinations, unaudited pro forma information, description	These unaudited pro forma financial results represent the results of operations of the companies acquired as if the acquired companies had been consolidated as of the beginning of the year prior to their acquisition, and are provided for illustrative purposes only. These unaudited pro forma financial results 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 Company’s unaudited pro forma financial results were prepared by adjusting the historical results of MasTec to include the unaudited historical results of the acquired businesses described above, and then adjusted for (i) acquisition costs; (ii) amortization expense resulting from the acquired intangible assets; (iii) interest expense as a result of the cash consideration paid; (iv) interest expense from debt repaid upon acquisition; and (iv) elimination of the effects of intercompany transactions and other purchase accounting related adjustments. These unaudited 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 the Company’s control.
Business combinations, consolidated acquisition-related revenue	$ 154.4	160.1
Business combinations, consolidated acquisition-related net income	$ 1.4	$ 10.2

Fair Value of Financial Instr_3

Fair Value of Financial Instruments (Acquisition-Related Contingent Consideration) (Narrative) (Details) - USD ($)		12 Months Ended
		Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Fair Value, Financial Instruments Measured on a Recurring Basis [Line Items]
Acquisition-related contingent consideration liabilities, range of potential undiscounted earn-out liabilities, low		$ 30,000,000
Acquisition-related contingent consideration liabilities, range of potential undiscounted earn-out liabilities, high		$ 157,000,000
Acquisition-related contingent consideration liabilities, range of potential earn-out liabilities, maximum unlimited		there is no maximum payment amount
Acquisition-related contingent consideration liabilities, net increase (decrease), measurement period adjustments	[1]	$ 4,600,000
Earn-Out Liabilities [Member]
Fair Value, Financial Instruments Measured on a Recurring Basis [Line Items]
Acquisition-related contingent consideration liabilities, estimated fair value		118,100,000	$ 117,200,000
Acquisition-related contingent consideration liabilities, additions from new business combinations		1,500,000	102,500,000	$ 0
Acquisition-related contingent consideration liabilities, net increase (decrease), measurement period adjustments		5,000,000
Acquisition-related contingent consideration liabilities, fair value adjustments, net increase (decrease), loss (gain) recorded in earnings		17,500,000	(12,300,000)	2,700,000
Acquisition-related contingent consideration liabilities, payments		23,100,000	18,800,000	$ 15,800,000
Earn-Out Liabilities [Member] | Other Current Liabilities [Member]
Fair Value, Financial Instruments Measured on a Recurring Basis [Line Items]
Acquisition-related contingent consideration liabilities, estimated fair value		$ 29,600,000	$ 22,600,000
[1]	Represents adjustments to preliminary estimates of fair value within the measurement period of up to one year from the date of acquisition.

Fair Value of Financial Instr_4

Fair Value of Financial Instruments (Equity Investments) (Narrative) (Details) - USD ($)	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017
Fair Value, Financial Instruments Measured on a Non-Recurring Basis [Line Items]
Equity investments, adjusted cost basis, amount	$ 18,000,000	$ 18,000,000
Equity investments, impairments	0	0
Equity Investee [Member]
Fair Value, Financial Instruments Measured on a Non-Recurring Basis [Line Items]
Equity investments, carrying value	197,000,000	141,000,000
CCI [Member]
Fair Value, Financial Instruments Measured on a Non-Recurring Basis [Line Items]
Equity investments, adjusted cost basis, amount	$ 15,000,000
Waha JVs [Member]
Fair Value, Financial Instruments Measured on a Non-Recurring Basis [Line Items]
Equity method investment, ownership percentage	33.00%
Waha JVs [Member] | Equity Investee [Member]
Fair Value, Financial Instruments Measured on a Non-Recurring Basis [Line Items]
Equity investments, carrying value	$ 168,000,000	$ 121,000,000

Fair Value of Financial Instr_5

Fair Value of Financial Instruments (The Waha JVs) (Narrative) (Details)	12 Months Ended
	Dec. 31, 2018USD ($)pipeline	Dec. 31, 2017USD ($)	Dec. 31, 2016USD ($)
Fair Value, Financial Instruments Measured on a Non-Recurring Basis [Line Items]
Letters of credit issued	$ 128,400,000	$ 157,100,000
Equity method investments, equity in earnings (losses)	23,855,000	21,328,000	$ 3,528,000
Unrealized gains on equity investee activity, net of tax	5,863,000	475,000	3,952,000
Equity Investee [Member]
Fair Value, Financial Instruments Measured on a Non-Recurring Basis [Line Items]
Equity method investments, net investment	197,000,000	141,000,000
Credit Facility [Member]
Fair Value, Financial Instruments Measured on a Non-Recurring Basis [Line Items]
Letters of credit issued	$ 88,200,000	157,100,000
Waha JVs [Member]
Fair Value, Financial Instruments Measured on a Non-Recurring Basis [Line Items]
Number of pipelines in operation | pipeline	2
Equity method investments, equity and other contributions	$ 28,000,000	73,000,000	27,000,000
Equity method investments, equity in earnings (losses)	23,900,000	21,300,000
Equity method investments, cumulative undistributed earnings	29,900,000
Equity method investments, distributions of earnings received, operating cash flows	10,900,000
Revenue, related parties		256,100,000	245,000,000
Receivables, net of BIEC, related parties		2,800,000
Unrealized gains on equity investee activity	7,700,000	800,000	6,400,000
Unrealized gains on equity investee activity, net of tax	5,900,000	500,000	$ 4,000,000
Waha JVs [Member] | Equity Investee [Member]
Fair Value, Financial Instruments Measured on a Non-Recurring Basis [Line Items]
Equity method investments, net investment	168,000,000	121,000,000
Waha JVs [Member] | Credit Facility [Member]
Fair Value, Financial Instruments Measured on a Non-Recurring Basis [Line Items]
Letters of credit issued	$ 0	$ 19,000,000

Fair Value of Financial Instr_6

Fair Value of Financial Instruments (Other Investments - Pensare) (Narrative) (Details) - Pensare [Member] $ / shares in Units, warrant in Millions, $ in Millions	Dec. 31, 2018warrant$ / shares	Sep. 30, 2017USD ($)
Fair Value, Financial Instruments Measured on a Non-Recurring Basis [Line Items]
Equity investment and warrants, amount paid (in dollars) | $		$ 2
Equity investment, ownership percentage	4.00%
Derivative instruments, number held | warrant	2
Plan [Member]
Fair Value, Financial Instruments Measured on a Non-Recurring Basis [Line Items]
Warrants, exercise price (in dollars per share) | $ / shares	$ 11.50
Plan [Member] | Common Stock [Member]
Fair Value, Financial Instruments Measured on a Non-Recurring Basis [Line Items]
Investment, restriction period (in years)	1 year

Fair Value of Financial Instr_7

Fair Value of Financial Instruments (Other Investments - Lifeshield) (Narrative) (Details) - USD ($) $ in Thousands	1 Months Ended	12 Months Ended
	Feb. 28, 2019	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Fair Value, Financial Instruments Measured on a Recurring Basis [Line Items]
Other investment, proceeds		$ 5,415	$ 23,801	$ 1,125
Lifeshield [Member]
Fair Value, Financial Instruments Measured on a Recurring Basis [Line Items]
Fair value investment, carrying amount		$ 10,000
Fair value investment, ownership percentage		40.00%
Lifeshield [Member] | Subsequent Event [Member]
Fair Value, Financial Instruments Measured on a Recurring Basis [Line Items]
Other investment, proceeds	$ 11,000

Fair Value of Financial Instr_8

Fair Value of Financial Instruments (Other Investments - Pacer) (Narrative) (Details) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Fair Value, Financial Instruments Measured on a Non-Recurring Basis [Line Items]
Other investment, proceeds									$ 5,415	$ 23,801	$ 1,125
Other current assets	$ 47,330				$ 35,763				47,330	35,763
Revenue	1,917,600	$ 1,977,200	$ 1,617,800	$ 1,396,800	1,602,900	$ 1,955,800	$ 1,890,200	$ 1,158,200	6,909,417	6,606,978	5,134,703
Pacer [Member] | Investment [Member]
Fair Value, Financial Instruments Measured on a Non-Recurring Basis [Line Items]
Other investment, changes in expected recovery estimates, (expense) income									(900)	(400)	3,600
Other investment, proceeds									5,400	22,500
Other current assets	$ 2,900				$ 9,600				$ 2,900	$ 9,600
Revenue											$ 600

Fair Value of Financial Instr_9

Fair Value of Financial Instruments (Schedule of Summarized Financial Information of Equity Method Investments) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Summarized Financial Information of Equity Method Investments [Line Items]
Current assets	$ 137.3	$ 136.8
Long-term assets	1,352.1	1,306.3
Total assets	1,489.4	1,443.1
Current liabilities	31.3	121.2
Long-term liabilities	966.1	976.5
Total liabilities	997.4	1,097.7
Revenue	145.8	114.5	$ 0
Net income (loss)	$ 72.4	$ 64.5	$ (0.2)

Fair Value of Financial Inst_10

Fair Value of Financial Instruments (Senior Notes) (Narrative) (Details) - USD ($) $ in Millions	Dec. 31, 2018	Dec. 31, 2017
Fair Value, Financial Instruments Measured on a Non-Recurring Basis [Line Items]
4.875% Senior Notes, gross carrying amount	$ 400	$ 400
Senior Notes [Member]
Fair Value, Financial Instruments Measured on a Non-Recurring Basis [Line Items]
4.875% Senior Notes, estimated fair value	$ 392	$ 410
4.875% Senior Notes [Member] | Senior Notes [Member]
Fair Value, Financial Instruments Measured on a Non-Recurring Basis [Line Items]
Debt instrument, interest rate (percentage)	4.875%

Accounts Receivable, Net of A_3

Accounts Receivable, Net of Allowance, and Contract Assets and Liabilities (Schedule of Accounts Receivable, Net of Allowance, and Contract Assets) (Details) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Accounts Receivable, Net of Allowance, and Contract Assets [Abstract]
Contract billings	$ 687,600	$ 683,900
Less allowance for doubtful accounts	(16,300)	(8,200)	$ (8,400)
Accounts receivables, net of allowance	671,300	675,700
Retainage	230,200	323,100
Cost and earnings in excess of billings	1,022,500	599,200
Retainage and costs and earnings in excess of billings (together, contract assets)	1,252,700	922,300
Accounts receivable, net	$ 1,923,970	$ 1,598,015

Accounts Receivable, Net of A_4

Accounts Receivable, Net of Allowance, and Contract Assets and Liabilities (Narrative) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Schedule of Accounts Receivable, Net of Allowance, and Contract Assets and Liabilities [Line Items]
Retainage, expected collection period (in years)	1 year
Billings in excess of costs and earnings	$ 227,056	$ 194,494
Revenue recognition, BIEC, revenue recognized	139,800
Contract liabilities	231,600	206,100
Receivables, Non-Recourse Arrangement [Member] | Interest Expense, Net [Member]
Schedule of Accounts Receivable, Net of Allowance, and Contract Assets and Liabilities [Line Items]
Non-recourse financing arrangement, discount charge	$ 11,100	$ 6,000	$ 2,700
Minimum [Member]
Schedule of Accounts Receivable, Net of Allowance, and Contract Assets and Liabilities [Line Items]
Retainage, percentage of contract billings	5.00%
Maximum [Member]
Schedule of Accounts Receivable, Net of Allowance, and Contract Assets and Liabilities [Line Items]
Retainage, percentage of contract billings	10.00%

Accounts Receivable, Net of A_5

Accounts Receivable, Net of Allowance, and Contract Assets and Liabilities (Schedule of Activity, Allowance for Doubtful Accounts) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017
Allowance for Doubtful Accounts [Rollforward]
Allowance for doubtful accounts at beginning of year	$ 8.2	$ 8.4
Provision for doubtful accounts	8.6	2.6
Amounts charged against the allowance	(0.5)	(2.8)
Allowance for doubtful accounts at end of year	$ 16.3	$ 8.2

Property and Equipment, Net (Sc

Property and Equipment, Net (Schedule of Property and Equipment, Net) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017
Property and Equipment [Line Items]
Property and equipment	$ 1,613,500	$ 1,455,600
Less accumulated depreciation and amortization	(865,700)	(749,100)
Property and equipment, net	747,808	706,506
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	$ 30,300	26,700
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	$ 1,391,800	1,261,900
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	$ 166,700	149,900
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	$ 20,100	$ 12,500

Property and Equipment, Net (Na

Property and Equipment, Net (Narrative) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Property and Equipment [Line Items]
Capitalized internal-use software, gross	$ 122,000	$ 109,900
Capitalized internal-use software, net	26,500	23,500
Depreciation and amortization	212,930	188,049	$ 164,915
Property and Equipment [Member]
Property and Equipment [Line Items]
Depreciation and amortization	$ 192,300	$ 167,200	$ 143,600

Debt (Schedule of Carrying Valu

Debt (Schedule of Carrying Values of Debt) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017
Debt Instrument [Line Items]
Capital lease obligations	$ 183,200	$ 181,200
Total long-term debt obligations	1,417,000	1,381,600
Less unamortized deferred financing costs	(10,100)	(13,000)
Total debt, net of deferred financing costs	1,406,900	1,368,600
Current portion of long-term debt	82,655	87,866
Long-term debt	$ 1,324,223	1,280,706
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	$ 456,900	377,700
Credit Facility [Member] | Term Loan [Member]
Debt Instrument [Line Items]
Long-term debt obligations	376,900	396,900
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)	3.90%
Capital lease obligations, expiration date, range, end	Dec. 31, 2023
Other Debt Obligations [Member]
Debt Instrument [Line Items]
Long-term debt obligations	$ 0	$ 25,800

Debt (Senior Secured Credit Fac

Debt (Senior Secured Credit Facility) (Narrative) (Details)	Dec. 31, 2018USD ($)NumberOfTimes	Dec. 31, 2017USD ($)	Dec. 31, 2017USD ($)	Mar. 31, 2018USD ($)	Dec. 31, 2018USD ($)NumberOfTimes
Debt Instrument [Line Items]
Line of credit facility, letters of credit issued	$ 128,400,000	$ 157,100,000	$ 157,100,000		$ 128,400,000
Credit Facility [Member]
Debt Instrument [Line Items]
Line of credit facility, maximum borrowing capacity	$ 1,500,000,000				1,500,000,000
Line of credit facility, unused credit facility commitment fee (percentage)	0.35%	0.25%
Line of credit facility, letters of credit issued	$ 88,200,000	$ 157,100,000	157,100,000		88,200,000
Credit Facility [Member] | 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%
Credit Facility [Member] | 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%
Credit Facility [Member] | 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%
Credit Facility [Member] | Plan [Member]
Debt Instrument [Line Items]
Line of credit facility, adjusted consolidated leverage ratio, permitted acquisitions amount, minimum threshold					50,000,000
Credit Facility [Member] | Maximum [Member]
Debt Instrument [Line Items]
Line of credit facility, revolving loans sublimit, Canadian dollars and/or Mexican pesos	$ 300,000,000				$ 300,000,000
Line of credit facility, unused credit facility commitment fee (percentage)	0.40%
Line of credit facility, required consolidated leverage ratio (in multiple)	3.50				3.50
Credit Facility [Member] | Maximum [Member] | Eurocurrency Rate [Member]
Debt Instrument [Line Items]
Line of credit facility, variable interest rate, margin over base rate (percentage)	2.00%
Credit Facility [Member] | Maximum [Member] | Base Rate [Member]
Debt Instrument [Line Items]
Line of credit facility, variable interest rate, margin over base rate (percentage)	1.00%
Credit Facility [Member] | Maximum [Member] | Plan [Member] | Permitted Acquisition [Member]
Debt Instrument [Line Items]
Line of credit facility, required consolidated leverage ratio (in multiple)	3.75				3.75
Line of credit facility, adjusted consolidated leverage ratio, permitted acquisitions, maximum number of times right may be exercised | NumberOfTimes	2				2
Credit Facility [Member] | Minimum [Member]
Debt Instrument [Line Items]
Line of credit facility, unused credit facility commitment fee (percentage)	0.20%
Line of credit facility, combined subsidiary guarantors percentage of consolidated EBITDA threshold (percentage)	70.00%				70.00%
Line of credit facility, individual domestic subsidiary guarantors percentage of consolidated EBITDA threshold (percentage)	15.00%				15.00%
Line of credit facility, required consolidated interest coverage ratio (in multiple)	3				3
Credit Facility [Member] | Minimum [Member] | Eurocurrency Rate [Member]
Debt Instrument [Line Items]
Line of credit facility, variable interest rate, margin over base rate (percentage)	1.25%
Credit Facility [Member] | Minimum [Member] | Base Rate [Member]
Debt Instrument [Line Items]
Line of credit facility, variable interest rate, margin over base rate (percentage)	0.25%
Credit Facility [Member] | Revolving Loans [Member]
Debt Instrument [Line Items]
Line of credit facility, maximum borrowing capacity	$ 1,100,000,000				$ 1,100,000,000
Line of credit facility, amount of borrowings denominated in foreign currencies	128,000,000	117,000,000	117,000,000		128,000,000
Line of credit facility, remaining borrowing capacity	554,900,000	565,200,000	565,200,000		554,900,000
Line of credit facility, remaining borrowing capacity in Canadian dollars or Mexican pesos	$ 91,900,000	$ 183,400,000	$ 183,400,000		$ 91,900,000
Credit Facility [Member] | Revolving Loans [Member] | Weighted Average [Member]
Debt Instrument [Line Items]
Line of credit facility, interest rate (percentage)	4.23%	3.69%	3.69%		4.23%
Credit Facility [Member] | Term Loan [Member]
Debt Instrument [Line Items]
Line of credit facility, maximum borrowing capacity	$ 400,000,000				$ 400,000,000
Line of credit facility, frequency of payments					quarterly
Line of credit facility, amount of quarterly principal installment payments			$ 3,100,000	$ 5,000,000
Line of credit facility, interest rate (percentage)	4.27%	3.07%	3.07%		4.27%
Credit Facility [Member] | Letters of Credit [Member]
Debt Instrument [Line Items]
Line of credit facility, maximum borrowing capacity	$ 650,000,000				$ 650,000,000
Line of credit facility, capacity available for letters of credit	$ 554,900,000	$ 492,900,000	$ 492,900,000		$ 554,900,000
Credit Facility [Member] | Letters of Credit [Member] | Commercial and/or Financial Standby [Member]
Debt Instrument [Line Items]
Line of credit facility, interest rate (percentage)	1.75%	1.50%	1.50%		1.75%
Credit Facility [Member] | Letters of Credit [Member] | Performance Standby [Member]
Debt Instrument [Line Items]
Line of credit facility, interest rate (percentage)	0.875%	0.625%	0.625%		0.875%
Credit Facility [Member] | Letters of Credit [Member] | Maximum [Member]
Debt Instrument [Line Items]
Line of credit facility, capacity available for letters of credit sublimit, Canadian dollars and/or Mexican pesos	$ 200,000,000				$ 200,000,000
Credit Facility [Member] | 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%
Credit Facility [Member] | Letters of Credit [Member] | Maximum [Member] | Performance Standby [Member]
Debt Instrument [Line Items]
Line of credit facility, interest rate (percentage)	1.00%				1.00%
Credit Facility [Member] | 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%				1.25%
Credit Facility [Member] | Letters of Credit [Member] | Minimum [Member] | Performance Standby [Member]
Debt Instrument [Line Items]
Line of credit facility, interest rate (percentage)	0.50%				0.50%
Credit Facility [Member] | Swing Line Loans [Member] | Maximum [Member]
Debt Instrument [Line Items]
Line of credit facility, swing line loans sublimit	$ 75,000,000				$ 75,000,000
Credit Facility [Member] | Accordion Feature [Member] | Plan [Member]
Debt Instrument [Line Items]
Line of credit facility, maximum borrowing capacity	$ 250,000,000				$ 250,000,000

Debt (Senior Secured Credit F_2

Debt (Senior Secured Credit Facility) (Terms, Guarantees and Covenants) (Narrative) (Details) - Credit Facility [Member]	12 Months Ended
	Dec. 31, 2018
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 Credit Facility, plus a margin of 1.25% to 2.00%, or (b) a Base Rate, as defined in the Credit Facility, plus a margin of 0.25% 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.
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, 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, 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, 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 cash 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 Credit Facility are subject to a letter of credit fee of 1.25% to 2.00%, and performance standby letters of credit are subject to a letter of credit fee of 0.50% to 1.00%.

Debt (Other Credit Facilities)

Debt (Other Credit Facilities) (Narrative) (Details) $ in Millions	12 Months Ended
	Dec. 31, 2018USD ($)	Dec. 31, 2018CAD ($)	Dec. 31, 2017USD ($)	Dec. 31, 2017CAD ($)
Debt Instrument [Line Items]
Letters of credit issued	$ 128,400,000		$ 157,100,000
Other Credit Facilities [Member]
Debt Instrument [Line Items]
Line of credit facility, maximum borrowing capacity (in dollars)		$ 20		$ 20
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.
Other Credit Facilities [Member] | Weighted Average [Member]
Debt Instrument [Line Items]
Line of credit facility, interest rate (percentage)			4.00%	4.00%
Other Credit Facilities [Member] | Canadian Dollars [Member]
Debt Instrument [Line Items]
Line of credit facility, maximum borrowing capacity (in dollars)	$ 14,700,000		$ 15,900,000
Long-term debt obligations (in dollars)	0		$ 10,400,000
Line of Credit [Member]
Debt Instrument [Line Items]
Letters of credit issued	40,200,000
Line of Credit [Member] | Letter of Credit [Member]
Debt Instrument [Line Items]
Line of credit facility, maximum borrowing capacity (in dollars)	$ 50,000,000
Line of Credit [Member] | Letter of Credit [Member] | Standby Letters of Credit [Member]
Debt Instrument [Line Items]
Line of credit facility, interest rate (percentage)	0.75%	0.75%

Debt (4.875% Senior Notes) (Nar

Debt (4.875% Senior Notes) (Narrative) (Details) - Senior Notes [Member] - 4.875% Senior Notes [Member]	12 Months Ended
	Dec. 31, 2018USD ($)
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	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.
Debt instrument, redemption description	The Company has the option to redeem all or a portion of the 4.875% Senior Notes at any time 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, 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.
Plan [Member] | Maximum [Member]
Debt Instrument [Line Items]
Debt instrument, percentage of principal that may be redeemed	100.00%

Debt (Schedule of Contractual M

Debt (Schedule of Contractual Maturities of Debt and Capital Lease Obligations) (Details) - USD ($) $ in Millions	Dec. 31, 2018	Dec. 31, 2017
Contractual Maturities of Debt and Capital Lease Obligations
Contractual maturities of debt and capital lease obligations, 2019	$ 83.1
Contractual maturities of debt and capital lease obligations, 2020	76.2
Contractual maturities of debt and capital lease obligations, 2021	63.4
Contractual maturities of debt and capital lease obligations, 2022	792.9
Contractual maturities of debt and capital lease obligations, 2023	401.4
Contractual maturities of debt and capital lease obligations, thereafter	0
Total long-term debt obligations	$ 1,417	$ 1,381.6

Debt (Other) (Narrative) (Detai

Debt (Other) (Narrative) (Details) - USD ($) $ in Millions	Dec. 31, 2018	Dec. 31, 2017
Debt Disclosure [Abstract]
Debt instruments, accrued interest payable	$ 7.4	$ 7.4

Lease Obligations (Capital Leas

Lease Obligations (Capital Leases) (Narrative) (Details) - Property and Equipment [Member] - USD ($) $ in Millions	Dec. 31, 2018	Dec. 31, 2017
Capital Leases [Line Items]
Assets held under capital lease, gross	$ 337.6	$ 418
Assets held under capital lease, net	$ 246.8	$ 277.3

Lease Obligations (Operating Le

Lease Obligations (Operating Leases) (Narrative) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Lease Terms in Excess of One Year [Member]
Operating Leases [Line Items]
Operating leases, rent and related expense (in dollars)	$ 115	$ 104.2	$ 100.5
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)	$ 472.1	$ 461	$ 298
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

Lease Obligations (Schedule of Future Lease Commitments) (Details) - USD ($) $ in Millions	Dec. 31, 2018	Dec. 31, 2017
Capital Leases
Future minimum lease commitments, 2019	$ 68.2
Future minimum lease commitments, 2020	60.2
Future minimum lease commitments, 2021	46.7
Future minimum lease commitments, 2022	20
Future minimum lease commitments, 2023	1.5
Future minimum lease commitments, thereafter	0
Total minimum lease payments	196.6
Less amounts representing interest	(13.4)
Total capital lease obligations, net of interest	183.2	$ 181.2
Less current portion	(63.1)
Long-term portion of capital lease obligations, net of interest	120.1
Operating Leases
Future minimum lease commitments, 2019	86.4
Future minimum lease commitments, 2020	60.4
Future minimum lease commitments, 2021	37.1
Future minimum lease commitments, 2022	21.7
Future minimum lease commitments, 2023	12.1
Future minimum lease commitments, thereafter	21.8
Total minimum lease payments	$ 239.5

Stock-Based Compensation and _3

Stock-Based Compensation and Other Employee Benefit Plans (Narrative) (Details) - USD ($) $ in Millions	3 Months Ended		12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Stock-Based Compensation and Other Employee Benefit Plans [Line Items]
Non-cash stock-based compensation expense (in dollars)			$ 13.5	$ 15.7	$ 15.1
Stock-based compensation, income tax benefits (in dollars)			4.9	11.2	5.6
Stock based compensation, vested awards, net income tax benefits (deficiency) (in dollars)	$ 1.3	$ 5.6	$ 1.6	$ 5.4	$ (0.1)
Employee Stock Purchase Plans [Member]
Stock-Based Compensation and Other Employee Benefit Plans [Line Items]
Stock-based compensation plans, description			The Company has certain employee stock purchase plans (collectively, “ESPPs”) under which shares of the Company’s common stock are available for purchase by eligible participants. These plans allow participants 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.
Common Stock [Member]
Stock-Based Compensation and Other Employee Benefit Plans [Line Items]
Stock-based compensation plans, number of shares available for future grant	4,429,000		4,429,000
2013 Incentive Plan [Member] | Restricted Shares [Member]
Stock-Based Compensation and Other Employee Benefit Plans [Line Items]
Stock-based compensation plans, 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] | Common Stock [Member] | Restricted Shares [Member]
Stock-Based Compensation and Other Employee Benefit Plans [Line Items]
Stock-based compensation plans, number of shares authorized	7,391,000		7,391,000
ESPPs [Member] | Employee Stock Purchase Plans [Member]
Stock-Based Compensation and Other Employee Benefit Plans [Line Items]
Stock-based compensation plans, description			Under the Company’s ESPPs, shares of the Company’s common stock are available for purchase by eligible participants, which collectively permit the issuance of up to 3,000,000 new shares of MasTec, Inc. common stock.
ESPPs [Member] | Common Stock [Member] | Employee Stock Purchase Plans [Member]
Stock-Based Compensation and Other Employee Benefit Plans [Line Items]
Stock-based compensation plans, number of shares authorized	3,000,000		3,000,000

Stock-Based Compensation and _4

Stock-Based Compensation and Other Employee Benefit Plans (Restricted Shares) (Narrative) (Details) - Restricted Shares [Member] - USD ($) $ in Millions	Dec. 31, 2018	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Stock-Based Compensation and Other Employee Benefit Plans [Line Items]
Stock-based compensation awards, unearned compensation	$ 24.4	$ 24.4
Stock-based compensation awards, unearned compensation, weighted average expected recognition period (in years)	2 years 3 months 18 days
Stock-based compensation, vested awards, intrinsic value		$ 16.6	$ 39.7	$ 3.5

Stock-Based Compensation and _5

Stock-Based Compensation and Other Employee Benefit Plans (Schedule of Activity, Restricted Shares) (Details) - Common Stock [Member] - $ / shares		12 Months Ended
		Dec. 31, 2018	Dec. 31, 2017
Restricted Shares [Member]
Restricted Shares
Non-vested restricted shares, beginning balance (in shares)	[1]	1,448,591	1,970,586
Granted (in shares)		423,596	429,061
Vested (in shares)		(554,900)	(899,815)
Canceled/forfeited (in shares)		(47,054)	(51,241)
Non-vested restricted shares, ending balance (in shares)	[1]	1,270,233	1,448,591
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)		$ 23.29	$ 21.61
Granted (in dollars per share)		41.41	40.46
Vested (in dollars per share)		17.73	28.08
Canceled/forfeited (in dollars per share)		22.26	18.22
Non-vested restricted shares, per share weighted average grant date fair value, ending balance (in dollars per share)		$ 31.80	$ 23.29
Restricted Stock Units [Member]
Restricted Shares
Non-vested restricted shares, beginning balance (in shares)		27,550	43,300
Non-vested restricted shares, ending balance (in shares)		18,700	27,550
[1]	Includes 18,700, 27,550 and 43,300 restricted stock units as of December 31, 2018, 2017 and 2016, respectively.

Stock-Based Compensation and _6

Stock-Based Compensation and Other Employee Benefit Plans (Schedule of Employee Stock Purchase Plans) (Details) - USD ($) $ / shares in Units, $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Common Stock [Member]
Stock-Based Compensation and Other Employee Benefit Plans [Line Items]
Common shares issued (in shares)	110,506	92,145	144,183
Employee Stock Purchase Plans [Member]
Stock-Based Compensation and Other Employee Benefit Plans [Line Items]
Cash proceeds (in dollars)	$ 4.2	$ 3.3	$ 2.7
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)	$ 37.98	$ 35.92	$ 18.55
Weighted average per share grant date fair value (in dollars per share)	$ 9.36	$ 9.24	$ 5

Stock-Based Compensation and _7

Stock-Based Compensation and Other Employee Benefit Plans (Stock Options) (Narrative) (Details) $ in Millions	12 Months Ended
	Dec. 31, 2016USD ($)
Share-based Compensation [Abstract]
Stock options exercised, intrinsic value	$ 1.8
Stock options exercised, proceeds, net of shares withheld	$ 2.1

Stock-Based Compensation and _8

Stock-Based Compensation and Other Employee Benefit Plans (401(k) Plan) (Narrative) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
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)	$ 13.4	$ 11.9	$ 11.1
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 _9

Stock-Based Compensation and Other Employee Benefit Plans (Deferred Compensation Plans) (Narrative) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017
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	$ 10	$ 9.4
Deferred compensation plans, liabilities	$ 10.2	$ 9.7

Other Retirement Plans (Narrati

Other Retirement Plans (Narrative) (Details)	12 Months Ended
	Dec. 31, 2018
Multiemployer Plans [Line Items]
Multiemployer plans, general nature	certain of MasTec’s subsidiaries, including certain subsidiaries in Canada, 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 (Schedul

Other Retirement Plans (Schedule of Multiemployer Pension Plans) (Details) - USD ($) $ in Millions		12 Months Ended
		Dec. 31, 2018		Dec. 31, 2017		Dec. 31, 2016
Multiemployer Plans [Line Items]
Multiemployer plans, contributions (in dollars)		$ 99.7		$ 102.4		$ 70
Multiemployer Plans, Pension [Member]
Multiemployer Plans [Line Items]
Multiemployer plans, contributions (in dollars)		$ 92.4		92.1		59.9
Multiemployer Plans, Pension [Member] | Pipeline Industry Pension Fund [Member]
Multiemployer Plans [Line Items]
Multiemployer plans, employer identification number		736,146,433
Multiemployer plans, plan number		1
Multiemployer plans, contributions (in dollars)		$ 20.7		$ 28.8		15.9
Multiemployer plans, collective bargaining arrangement, expiration date		May 31, 2020
Multiemployer plans, pension protection act zone status		Green		Green
Multiemployer plans, pension protection act zone status, date	[1]	Dec. 31, 2017		Dec. 31, 2016
Multiemployer plans, Company contributions greater than 5% of total plan contributions		true		true
Multiemployer plans, funding improvement plan and rehabilitation plan status		NA
Multiemployer plans, surcharge status		No
Multiemployer Plans, Pension [Member] | Central Pension Fund of IUOE & Participating Employers [Member]
Multiemployer Plans [Line Items]
Multiemployer plans, employer identification number		366,052,390
Multiemployer plans, plan number		1
Multiemployer plans, contributions (in dollars)		$ 20.4		$ 21.6		19.3
Multiemployer plans, collective bargaining arrangement, expiration date		May 31, 2020
Multiemployer plans, pension protection act zone status		Green		Green
Multiemployer plans, pension protection act zone status, date		Jan. 31, 2018		Jan. 31, 2017
Multiemployer plans, funding improvement plan and rehabilitation plan status		NA
Multiemployer plans, surcharge status		No
Multiemployer Plans, Pension [Member] | Teamsters National Pipe Line Pension Plan [Member]
Multiemployer Plans [Line Items]
Multiemployer plans, employer identification number		461,102,851
Multiemployer plans, plan number		1
Multiemployer plans, contributions (in dollars)		$ 7.4		$ 7.6		3.6
Multiemployer plans, collective bargaining arrangement, expiration date		May 31, 2020
Multiemployer plans, pension protection act zone status		Green		Green
Multiemployer plans, pension protection act zone status, date	[1]	Dec. 31, 2017		Dec. 31, 2016
Multiemployer plans, Company contributions greater than 5% of total plan contributions		true		true
Multiemployer plans, funding improvement plan and rehabilitation plan status		NA
Multiemployer plans, surcharge status		No
Multiemployer Plans, Pension [Member] | International Union of Operating Engineers Local 132 Pension Fund [Member]
Multiemployer Plans [Line Items]
Multiemployer plans, employer identification number		556,015,364
Multiemployer plans, plan number		1
Multiemployer plans, contributions (in dollars)		$ 5.6		$ 2.3		0.2
Multiemployer plans, collective bargaining arrangement, expiration date		May 31, 2020
Multiemployer plans, pension protection act zone status		Green		Green
Multiemployer plans, pension protection act zone status, date		Mar. 31, 2018		Mar. 31, 2017
Multiemployer plans, funding improvement plan and rehabilitation plan status		NA
Multiemployer plans, surcharge status		No
Multiemployer Plans, Pension [Member] | West Virginia Laborers' Pension Trust Fund [Member]
Multiemployer Plans [Line Items]
Multiemployer plans, employer identification number		556,026,775
Multiemployer plans, plan number		1
Multiemployer plans, contributions (in dollars)		$ 4.5		$ 3		0.5
Multiemployer plans, collective bargaining arrangement, expiration date		May 31, 2020
Multiemployer plans, pension protection act zone status		Green		Green
Multiemployer plans, pension protection act zone status, date		Mar. 31, 2018	[1]	Mar. 31, 2017
Multiemployer plans, Company contributions greater than 5% of total plan contributions		true
Multiemployer plans, funding improvement plan and rehabilitation plan status		NA
Multiemployer plans, surcharge status		No
Multiemployer Plans, Pension [Member] | Laborers' National Pension Fund [Member]
Multiemployer Plans [Line Items]
Multiemployer plans, employer identification number		751,280,827
Multiemployer plans, plan number		1
Multiemployer plans, contributions (in dollars)		$ 4.1		$ 3.5		3
Multiemployer plans, collective bargaining arrangement, expiration date		May 31, 2020
Multiemployer plans, pension protection act zone status		Red		Green
Multiemployer plans, pension protection act zone status, date		Dec. 31, 2017		Dec. 31, 2016
Multiemployer plans, funding improvement plan and rehabilitation plan status		Implemented
Multiemployer plans, surcharge status		No
Multiemployer Plans, Pension [Member] | Laborers' Pension Fund of Roanoke, Virginia [Member]
Multiemployer Plans [Line Items]
Multiemployer plans, employer identification number		546,111,015
Multiemployer plans, plan number		1
Multiemployer plans, contributions (in dollars)		$ 2.5		$ 0.1		0.2
Multiemployer plans, collective bargaining arrangement, expiration date		May 31, 2020
Multiemployer plans, pension protection act zone status		Green		Green
Multiemployer plans, pension protection act zone status, date		Sep. 30, 2017		Sep. 30, 2016	[1]
Multiemployer plans, Company contributions greater than 5% of total plan contributions				true
Multiemployer plans, funding improvement plan and rehabilitation plan status		NA
Multiemployer plans, surcharge status		No
Multiemployer Plans, Pension [Member] | IBEW Local 1249 Pension Plan [Member]
Multiemployer Plans [Line Items]
Multiemployer plans, employer identification number		156,035,161
Multiemployer plans, plan number		1
Multiemployer plans, contributions (in dollars)		$ 2.2		$ 1.5		1.1
Multiemployer plans, collective bargaining arrangement, expiration date		May 2, 2021
Multiemployer plans, pension protection act zone status		Yellow		Yellow
Multiemployer plans, pension protection act zone status, date		Dec. 31, 2017		Dec. 31, 2016
Multiemployer plans, funding improvement plan and rehabilitation plan status		Implemented
Multiemployer plans, surcharge status		No
Multiemployer Plans, Pension [Member] | Ohio Operating Engineers Pension Plan [Member]
Multiemployer Plans [Line Items]
Multiemployer plans, employer identification number		316,129,968
Multiemployer plans, plan number		1
Multiemployer plans, contributions (in dollars)		$ 2.1		$ 4.9		0
Multiemployer plans, collective bargaining arrangement, expiration date		May 31, 2020
Multiemployer plans, pension protection act zone status		Green		Green
Multiemployer plans, pension protection act zone status, date		Jul. 31, 2017		Jul. 31, 2016
Multiemployer plans, funding improvement plan and rehabilitation plan status		NA
Multiemployer plans, surcharge status		No
Multiemployer Plans, Pension [Member] | Laborers' Local Union No. 158 Pension Plan [Member]
Multiemployer Plans [Line Items]
Multiemployer plans, employer identification number		236,580,323
Multiemployer plans, plan number		1
Multiemployer plans, contributions (in dollars)		$ 1.5		$ 1.8		0.4
Multiemployer plans, collective bargaining arrangement, expiration date		Apr. 30, 2020
Multiemployer plans, pension protection act zone status		Green		Green
Multiemployer plans, pension protection act zone status, date		Dec. 31, 2017	[1]	Dec. 31, 2016
Multiemployer plans, Company contributions greater than 5% of total plan contributions		true
Multiemployer plans, funding improvement plan and rehabilitation plan status		NA
Multiemployer plans, surcharge status		No
Multiemployer Plans, Pension [Member] | Employer- Teamsters Local Nos. 175 & 505 Pension Trust Fund [Member]
Multiemployer Plans [Line Items]
Multiemployer plans, employer identification number		556,021,850
Multiemployer plans, plan number		1
Multiemployer plans, contributions (in dollars)		$ 1.5		$ 0.3		0
Multiemployer plans, collective bargaining arrangement, expiration date		May 31, 2020
Multiemployer plans, pension protection act zone status		Red		Red
Multiemployer plans, pension protection act zone status, date	[2]	Dec. 31, 2017		Dec. 31, 2016
Multiemployer plans, pension protection act zone status, extended amortization provisions		true		true
Multiemployer plans, funding improvement plan and rehabilitation plan status		Implemented
Multiemployer plans, surcharge status		No
Multiemployer Plans, Pension [Member] | Michigan Laborers' Pension Plan [Member]
Multiemployer Plans [Line Items]
Multiemployer plans, employer identification number		386,233,976
Multiemployer plans, plan number		1
Multiemployer plans, contributions (in dollars)		$ 1.5		$ 2		1.1
Multiemployer plans, collective bargaining arrangement, expiration date		May 31, 2020
Multiemployer plans, pension protection act zone status		Yellow		Yellow
Multiemployer plans, pension protection act zone status, date		Aug. 31, 2018		Aug. 31, 2017	[2]
Multiemployer plans, pension protection act zone status, extended amortization provisions				true
Multiemployer plans, funding improvement plan and rehabilitation plan status		Implemented
Multiemployer plans, surcharge status		No
Multiemployer Plans, Pension [Member] | National Electrical Benefit Fund [Member]
Multiemployer Plans [Line Items]
Multiemployer plans, employer identification number		530,181,657
Multiemployer plans, plan number		1
Multiemployer plans, contributions (in dollars)		$ 1.4		$ 1.8		1.7
Multiemployer plans, pension protection act zone status		Green		Green
Multiemployer plans, pension protection act zone status, date		Dec. 31, 2017		Dec. 31, 2016
Multiemployer plans, funding improvement plan and rehabilitation plan status		NA
Multiemployer plans, surcharge status		No
Multiemployer Plans, Pension [Member] | National Electrical Benefit Fund [Member] | Maximum [Member]
Multiemployer Plans [Line Items]
Multiemployer plans, collective bargaining arrangement, expiration date		May 31, 2021
Multiemployer Plans, Pension [Member] | Laborers' District Council of Western Pennsylvania Pension Fund [Member]
Multiemployer Plans [Line Items]
Multiemployer plans, employer identification number		256,135,576
Multiemployer plans, plan number		1
Multiemployer plans, contributions (in dollars)		$ 1.4		$ 0.6		0.2
Multiemployer plans, collective bargaining arrangement, expiration date		Dec. 31, 2020
Multiemployer plans, pension protection act zone status		Red		Red
Multiemployer plans, pension protection act zone status, date		Dec. 31, 2017		Dec. 31, 2016
Multiemployer plans, funding improvement plan and rehabilitation plan status		Implemented
Multiemployer plans, surcharge status		No
Multiemployer Plans, Pension [Member] | Operating Engineers' Local 324 Pension Fund [Member]
Multiemployer Plans [Line Items]
Multiemployer plans, employer identification number		381,900,637
Multiemployer plans, plan number		1
Multiemployer plans, contributions (in dollars)		$ 0.6		$ 2.1		0
Multiemployer plans, collective bargaining arrangement, expiration date		May 31, 2020
Multiemployer plans, pension protection act zone status		Red		Red
Multiemployer plans, pension protection act zone status, date		Apr. 30, 2018		Apr. 30, 2017
Multiemployer plans, funding improvement plan and rehabilitation plan status		Implemented
Multiemployer plans, surcharge status		No
Multiemployer Plans, Pension [Member] | Other Funds [Member]
Multiemployer Plans [Line Items]
Multiemployer plans, contributions (in dollars)	[3]	$ 15		$ 10.2		12.7
Multiemployer Plans, Pension [Member] | Other Funds [Member] | Canada [Member]
Multiemployer Plans [Line Items]
Multiemployer plans, contributions (in dollars)		$ 0.2		$ 0.7		$ 0.9
[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 2018, 2017 and 2016 contributions include approximately $0.2 million, $0.7 million and $0.9 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 (Sched_2

Other Retirement Plans (Schedule of Covered Employees and Contributions, Multiemployer Plans) (Details) $ in Millions	12 Months Ended
	Dec. 31, 2018USD ($)employee	Dec. 31, 2017USD ($)employee	Dec. 31, 2016USD ($)employee
Covered Employees and Contributions, Multiemployer Plans [Line Items]
Multiemployer plans, contributions (in dollars)	$ 99.7	$ 102.4	$ 70
Multiemployer Plans, Pension [Member]
Covered Employees and Contributions, Multiemployer Plans [Line Items]
Multiemployer plans, contributions (in dollars)	92.4	92.1	59.9
Multiemployer Plans, Other Multiemployer [Member]
Covered Employees and Contributions, Multiemployer Plans [Line Items]
Multiemployer plans, contributions (in dollars)	$ 7.3	$ 10.3	$ 10.1
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	1,626	550	550
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	6,336	7,057	4,910

Equity (Share Activity) (Narrat

Equity (Share Activity) (Narrative) (Details) - USD ($)	1 Months Ended	3 Months Ended		6 Months Ended	12 Months Ended
	Jan. 31, 2019	Dec. 31, 2018	Mar. 31, 2018	Sep. 30, 2018	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016	Dec. 21, 2018	Sep. 11, 2018	Mar. 29, 2018
Equity, Treasury Stock [Line Items]
Treasury stock acquired, value					$ 319,001,000	$ 1,551,000
Payments for repurchase of common stock					313,949,000	$ 1,552,000	$ 0
Share repurchase program, amount available for future share repurchases, value		$ 129,400,000			129,400,000
Subsequent Event [Member]
Equity, Treasury Stock [Line Items]
Payments for repurchase of common stock	$ 5,100,000
2016 Share Repurchase Program [Member]
Equity, Treasury Stock [Line Items]
Treasury stock acquired, value			$ 98,400,000
Share repurchase program, authorized amount, value							$ 100,000,000
March 2018 Share Repurchase Program [Member]
Equity, Treasury Stock [Line Items]
Share repurchase program, authorized amount, value										$ 100,000,000
September 2018 Share Repurchase Program [Member]
Equity, Treasury Stock [Line Items]
Treasury stock acquired, value		120,600,000
Share repurchase program, authorized amount, value									$ 150,000,000
Share repurchase program, amount available for future share repurchases, value		29,400,000			29,400,000
December 2018 Share Repurchase Program [Member]
Equity, Treasury Stock [Line Items]
Share repurchase program, authorized amount, value								$ 100,000,000
Share repurchase program, amount available for future share repurchases, value		$ 100,000,000			$ 100,000,000
Treasury Stock, Common [Member]
Equity, Treasury Stock [Line Items]
Treasury stock acquired (in shares)					7,197,006	38,807	0
Treasury stock acquired, value					$ 319,001,000	$ 1,551,000
Treasury Stock, Common [Member] | 2016 Share Repurchase Program [Member]
Equity, Treasury Stock [Line Items]
Treasury stock acquired (in shares)			2,000,000
Treasury Stock, Common [Member] | March 2018 Share Repurchase Program [Member]
Equity, Treasury Stock [Line Items]
Treasury stock acquired (in shares)				2,300,000
Treasury Stock, Common [Member] | September 2018 Share Repurchase Program [Member]
Equity, Treasury Stock [Line Items]
Treasury stock acquired (in shares)		2,900,000

Equity (Rollforward of Accumula

Equity (Rollforward of Accumulated Other Comprehensive Loss) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Accumulated Other Comprehensive Loss [Line Items]
Accumulated other comprehensive loss, beginning balance	$ (63,712)	$ (65,814)	$ (72,351)
Unrealized (losses) gains, net of tax	3,218	2,102	6,537
Accumulated other comprehensive loss, ending balance	(60,494)	(63,712)	(65,814)
Foreign Currency [Member]
Accumulated Other Comprehensive Loss [Line Items]
Accumulated other comprehensive loss, beginning balance	(62,851)	(64,478)	(67,063)
Unrealized (losses) gains, net of tax	(2,645)	1,627	2,585
Accumulated other comprehensive loss, ending balance	(65,496)	(62,851)	(64,478)
Other [Member]
Accumulated Other Comprehensive Loss [Line Items]
Accumulated other comprehensive loss, beginning balance	(861)	(1,336)	(5,288)
Unrealized (losses) gains, net of tax	5,863	475	3,952
Accumulated other comprehensive loss, ending balance	$ 5,002	$ (861)	$ (1,336)

Income Taxes (Schedule of Compo

Income Taxes (Schedule of Components of Income before Income Taxes) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Income Tax Disclosure [Abstract]
Domestic	$ 341,100	$ 334,900	$ 202,400
Foreign	24,200	36,900	23,400
Income before income taxes	$ 365,303	$ 371,826	$ 225,819

Income Taxes (Schedule of Provi

Income Taxes (Schedule of Provision for Income Taxes) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Current:
Federal	$ 26,700	$ (6,000)	$ 85,800
Foreign	9,400	11,500	3,000
State and local	10,500	(800)	6,700
Total current income tax expense	46,600	4,700	95,500
Deferred:
Federal	43,900	18,200	6,100
Foreign	3,300	(7,500)	(6,800)
State and local	12,300	7,600	(3,000)
Total deferred income tax expense	56,209	18,277	(3,935)
Provision for income taxes	106,072	22,942	91,784
Continuing Operations [Member]
Deferred:
Total deferred income tax expense	$ 59,500	$ 18,300	$ (3,700)

Income Taxes (Schedule of Defer

Income Taxes (Schedule of Deferred Tax Assets and Liabilities) (Details) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Deferred tax assets:
Accrued insurance	$ 25,900	$ 24,600
Operating loss carryforwards and tax credits	67,700	54,900
Compensation and benefits	15,200	7,500
Bad debt	2,400	1,200
Unrealized gains and losses	0	11,400
Other	8,400	7,900
Valuation allowance	(40,600)	(40,500)
Total deferred tax assets	79,000	67,000
Deferred tax liabilities:
Property and equipment	146,300	104,100
Goodwill	55,600	56,700
Other intangible assets	28,100	28,700
Revenue recognition	21,600	11,300
Investments in unconsolidated entities	67,900	52,800
Other	16,100	11,000
Total deferred tax liabilities	342,700	271,500
Net deferred tax liabilities	(263,687)	(204,518)
Equity Investee [Member]
Deferred tax liabilities:
Gain on remeasurement of equity investee	$ 7,100	$ 6,900

Income Taxes (Narrative) (Detai

Income Taxes (Narrative) (Details) - USD ($)	3 Months Ended				12 Months Ended
	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Dec. 31, 2017	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Income Taxes [Line Items]
Valuation allowance, methodologies and assumptions					In assessing the ability to realize the Company’s deferred tax assets, management considers whether it is more likely than not that some portion, or all, of its 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 Company’s projected future taxable income and prudent and feasible tax planning strategies in making this assessment.
Net operating loss carryforwards, deferred tax assets	$ 67,700,000			$ 54,900,000	$ 67,700,000	$ 54,900,000
U.S. corporate tax rate, percent					21.00%	35.00%	35.00%
Change in enacted tax rate, non-cash tax benefit (in dollars)	(3,700,000)	$ 17,900,000	$ (1,500,000)	120,100,000	$ 16,400,000	$ 120,100,000
Provision for U.S. income taxes not recognized, unremitted foreign earnings	0				0
Unrecognized tax benefits, accrued interest and penalties	800,000				800,000
Unrecognized tax benefits, interest and penalties, income tax expense					700,000
Unrecognized tax benefits	9,400,000				9,400,000
State [Member]
Income Taxes [Line Items]
Net operating loss carryforwards, deferred tax assets	11,900,000			12,300,000	$ 11,900,000	12,300,000
State [Member] | Earliest Tax Year [Member]
Income Taxes [Line Items]
Net operating loss carryforwards, expiration date					Dec. 31, 2023
State [Member] | Latest Tax Year [Member]
Income Taxes [Line Items]
Net operating loss carryforwards, expiration date					Dec. 31, 2038
Foreign [Member]
Income Taxes [Line Items]
Net operating loss carryforwards, deferred tax assets	50,800,000			38,400,000	$ 50,800,000	38,400,000
Foreign [Member] | Earliest Tax Year [Member] | Canada [Member]
Income Taxes [Line Items]
Net operating loss carryforwards, expiration date					Jan. 1, 2033
Federal [Member]
Income Taxes [Line Items]
Net operating loss carryforwards, deferred tax assets	$ 200,000			$ 200,000	$ 200,000	$ 200,000
Federal [Member] | Earliest Tax Year [Member]
Income Taxes [Line Items]
Net operating loss carryforwards, expiration date					Jan. 1, 2022

Income Taxes (Schedule of Effec

Income Taxes (Schedule of Effective Tax Rate Reconciliation) (Details)	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Income Tax Disclosure [Abstract]
U.S. statutory federal rate applied to pretax income	21.00%	35.00%	35.00%
State and local income taxes, net of federal benefit	4.20%	2.00%	2.60%
Foreign tax rate differential	1.50%	0.30%	(0.10%)
Non-deductible expenses	1.70%	2.20%	4.40%
Goodwill and intangible assets	3.60%	0.00%	(0.70%)
Change in tax rate	(2.80%)	(32.30%)	(1.90%)
Domestic production activities deduction	(0.00%)	(0.20%)	(2.90%)
Other	(2.40%)	(0.70%)	(0.10%)
Tax credits	(0.40%)	(2.80%)	(0.00%)
Valuation allowance for deferred tax assets	2.60%	2.70%	4.30%
Effective income tax rate	29.00%	6.20%	40.60%

Income Taxes (Rollforward of Un

Income Taxes (Rollforward of Uncertain Tax Positions) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Uncertain Tax Positions [Rollforward]
Beginning balance	$ 8.1	$ 0	$ 0
Additions based on tax positions related to the current year	2.7	3.2	0
Additions for tax positions of prior years	0	4.9	0
Reductions for tax positions of prior years	(1.4)	0	0
Ending balance	$ 9.4	$ 8.1	$ 0

Segments and Related Informat_3

Segments and Related Information (Narrative) (Details) $ in Thousands	3 Months Ended			12 Months Ended
	Dec. 31, 2018USD ($)	Jun. 30, 2018USD ($)	Mar. 31, 2017USD ($)	Dec. 31, 2018USD ($)segment	Dec. 31, 2017USD ($)	Dec. 31, 2016USD ($)
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 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, which is recorded within corporate results, is managed on a consolidated basis and is not allocated to the reportable segments.
Goodwill, pre-tax impairment charge (in dollars)	$ 47,700			$ 47,662	$ 0	$ 0
Pacer [Member] | Joint Venture [Member]
Segment and Related Information [Line Items]
Project gains (in dollars)		$ 1,000		$ 1,000
Project losses (in dollars)			$ 7,000		$ 7,900	5,100
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.
Goodwill, pre-tax impairment charge (in dollars)				$ 0
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.
Goodwill, pre-tax impairment charge (in dollars)				$ 47,700
Project losses (in dollars)						13,500
Restructuring charges (in dollars)						6,300
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.
Goodwill, pre-tax impairment charge (in dollars)				$ 0
Project losses (in dollars)						15,100
Restructuring charges (in dollars)						$ 8,900
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 power facilities, including renewables, related electrical transmission infrastructure, ethanol/biofuel facilities and various types of heavy civil and industrial infrastructure.
Goodwill, pre-tax impairment charge (in dollars)				$ 0

Segments and Related Informat_4

Segments and Related Information (Schedule of Financial Information by Reportable Segment - Revenue) (Details) - USD ($) $ in Thousands		3 Months Ended								12 Months Ended
		Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Revenue:
Revenue (in dollars)		$ 1,917,600	$ 1,977,200	$ 1,617,800	$ 1,396,800	$ 1,602,900	$ 1,955,800	$ 1,890,200	$ 1,158,200	$ 6,909,417	$ 6,606,978	$ 5,134,703
Communications [Member] | Customer Concentration Risk [Member] | Revenue [Member] | Utilities [Member]
Revenue:
Utilities customers, percentage of Communications segment revenue										14.90%	13.40%	11.10%
Reportable Segments [Member] | Communications [Member]
Revenue:
Revenue (in dollars)	[1]									$ 2,556,800	$ 2,424,400	$ 2,323,600
Reportable Segments [Member] | Oil and Gas [Member]
Revenue:
Revenue (in dollars)										3,288,700	3,497,200	2,024,400
Reportable Segments [Member] | Electrical Transmission [Member]
Revenue:
Revenue (in dollars)										397,300	378,200	383,800
Reportable Segments [Member] | Power Generation and Industrial [Member]
Revenue:
Revenue (in dollars)										665,000	299,900	405,700
Reportable Segments [Member] | Other [Member]
Revenue:
Revenue (in dollars)										3,500	20,800	15,900
Eliminations [Member]
Revenue:
Revenue (in dollars)										$ (1,900)	$ (13,500)	$ (18,700)
[1]	Revenue generated primarily by utilities customers represented 14.9%, 13.4% and 11.1% of Communications segment revenue for the years ended December 31, 2018, 2017 and 2016, respectively.

Segments and Related Informat_5

Segments and Related Information (Schedule of Financial Information by Reportable Segment - EBITDA) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
EBITDA:
EBITDA	$ 660.8	$ 620.9	$ 441.5
Reportable Segments [Member] | Communications [Member]
EBITDA:
EBITDA	290.4	247.4	244.6
Reportable Segments [Member] | Oil and Gas [Member]
EBITDA:
EBITDA	451.6	402.2	297.3
Reportable Segments [Member] | Electrical Transmission [Member]
EBITDA:
EBITDA	10.5	17.6	(42.9)
Reportable Segments [Member] | Power Generation and Industrial [Member]
EBITDA:
EBITDA	40.4	22.6	18.3
Reportable Segments [Member] | Other [Member]
EBITDA:
EBITDA	24.4	19.8	(2.6)
Corporate [Member]
EBITDA:
EBITDA	$ (156.4)	$ (88.7)	$ (73.1)

Segments and Related Informat_6

Segments and Related Information (Schedule of Financial Information by Reportable Segment - Depreciation and Amortization) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Depreciation and Amortization:
Depreciation and amortization	$ 212,930	$ 188,049	$ 164,915
Reportable Segments [Member] | Communications [Member]
Depreciation and Amortization:
Depreciation and amortization	59,300	53,200	50,300
Reportable Segments [Member] | Oil and Gas [Member]
Depreciation and Amortization:
Depreciation and amortization	113,700	96,700	78,400
Reportable Segments [Member] | Electrical Transmission [Member]
Depreciation and Amortization:
Depreciation and amortization	19,800	22,800	23,200
Reportable Segments [Member] | Power Generation and Industrial [Member]
Depreciation and Amortization:
Depreciation and amortization	13,700	9,100	6,200
Reportable Segments [Member] | Other [Member]
Depreciation and Amortization:
Depreciation and amortization	100	100	100
Corporate [Member]
Depreciation and Amortization:
Depreciation and amortization	$ 6,300	$ 6,100	$ 6,700

Segments and Related Informat_7

Segments and Related Information (Schedule of Financial Information by Reportable Segment - Assets) (Details) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Assets:
Assets	$ 4,439,953	$ 4,066,576	$ 3,183,100
Reportable Segments [Member] | Communications [Member]
Assets:
Assets	1,461,700	1,314,400	1,156,900
Reportable Segments [Member] | Oil and Gas [Member]
Assets:
Assets	1,965,300	1,762,600	1,267,200
Reportable Segments [Member] | Electrical Transmission [Member]
Assets:
Assets	423,900	471,400	419,100
Reportable Segments [Member] | Power Generation and Industrial [Member]
Assets:
Assets	358,700	288,600	268,100
Reportable Segments [Member] | Other [Member]
Assets:
Assets	193,900	153,200	27,700
Corporate [Member]
Assets:
Assets	$ 36,500	$ 76,400	$ 44,100

Segments and Related Informat_8

Segments and Related Information (Schedule of Financial Information by Reportable Segment - Capital Expenditures) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Capital Expenditures:
Capital expenditures	$ 180,420	$ 123,412	$ 117,114
Reportable Segments [Member] | Communications [Member]
Capital Expenditures:
Capital expenditures	69,300	40,500	28,500
Reportable Segments [Member] | Oil and Gas [Member]
Capital Expenditures:
Capital expenditures	83,500	57,700	64,000
Reportable Segments [Member] | Electrical Transmission [Member]
Capital Expenditures:
Capital expenditures	10,200	14,900	19,800
Reportable Segments [Member] | Power Generation and Industrial [Member]
Capital Expenditures:
Capital expenditures	6,500	5,400	3,400
Reportable Segments [Member] | Other [Member]
Capital Expenditures:
Capital expenditures	0	0	300
Corporate [Member]
Capital Expenditures:
Capital expenditures	$ 10,900	$ 4,900	$ 1,100

Segments and Related Informat_9

Segments and Related Information (Reconciliation of Consolidated Income before Income Taxes to EBITDA) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
EBITDA Reconciliation:
Income before income taxes	$ 365,303	$ 371,826	$ 225,819
Interest expense, net	82,571	61,011	50,734
Depreciation and amortization	212,930	188,049	164,915
EBITDA	$ 660,800	$ 620,900	$ 441,500

Segments and Related Informa_10

Segments and Related Information (Foreign Operations) (Narrative) (Details) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Segment and Related Information [Line Items]
Revenue				$ 1,917,600	$ 1,977,200	$ 1,617,800	$ 1,396,800	$ 1,602,900	$ 1,955,800	$ 1,890,200	$ 1,158,200	$ 6,909,417	$ 6,606,978	$ 5,134,703
Property and equipment, net	$ 747,808	$ 706,506		747,808				706,506				747,808	706,506
Intangible assets and goodwill, net	1,269,700	1,328,900		1,269,700				1,328,900				1,269,700	1,328,900
United States [Member]
Segment and Related Information [Line Items]
Revenue												6,700,000	6,400,000	4,900,000
Property and equipment, net	707,400	649,500	$ 475,300	707,400				649,500				707,400	649,500	475,300
Intangible assets and goodwill, net	1,200,000	1,200,000	1,100,000	1,200,000				1,200,000				1,200,000	1,200,000	1,100,000
Foreign Operations [Member]
Segment and Related Information [Line Items]
Revenue												164,300	211,500	279,700
Property and equipment, net	40,400	57,000	73,800	40,400				57,000				40,400	57,000	73,800
Intangible assets and goodwill, net	$ 61,500	$ 112,800	$ 107,800	$ 61,500				$ 112,800				$ 61,500	$ 112,800	$ 107,800
Foreign Operations [Member] | Accounts Receivable, Net, Less BIEC [Member] | Geographic Concentration Risk [Member]
Segment and Related Information [Line Items]
Concentration risk, percentage of total	5.00%	5.00%	8.00%

Segments and Related Informa_11

Segments and Related Information (Schedule of Significant Customers, Revenue Concentration Information) (Details) - Customer Concentration Risk [Member] - Revenue [Member]		12 Months Ended
		Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
AT&T (including DIRECTV) [Member]
Revenue, Significant Customer [Line Items]
Concentration risk, percentage of total	[1]	23.00%	25.00%	34.00%
EQT Corporation [Member]
Revenue, Significant Customer [Line Items]
Concentration risk, percentage of total	[2]	20.00%	0.00%	0.00%
Energy Transfer Affiliates [Member]
Revenue, Significant Customer [Line Items]
Concentration risk, percentage of total	[3]	14.00%	40.00%	27.00%
[1]	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.
[2]	The Company's relationship with EQT Corporation and its affiliates is based upon various construction contracts for pipeline activities. Revenue from EQT Corporation is included in the Oil and Gas segment.
[3]	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.

Commitments and Contingencies (

Commitments and Contingencies (Other Commitments and Contingencies) (Narrative) (Details) - USD ($) $ in Millions	Dec. 31, 2018	Dec. 31, 2017
Loss Contingencies [Line Items]
Letters of credit issued	$ 128.4	$ 157.1
Self-Insurance [Member] | Workers' Compensation, General and Automobile Policies [Member]
Loss Contingencies [Line Items]
Self-insurance reserve	108.9	106.2
Self-Insurance [Member] | Workers' Compensation, General and Automobile Policies [Member] | Other Long-Term Liabilities [Member]
Loss Contingencies [Line Items]
Self-insurance reserve, non-current	70.8	72.2
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	1.6
Self-Insurance [Member] | Employee Group Medical Claims Policy [Member]
Loss Contingencies [Line Items]
Self-insurance reserve	2.9	2.6
Performance and Payment Bonds [Member]
Loss Contingencies [Line Items]
Bonded projects, estimated costs to complete	53	46
Performance and Payment Bonds [Member] | Subsidiaries [Member]
Loss Contingencies [Line Items]
Outstanding bonds, amount	123.6	119.7
Financial Guarantees [Member] | Self-Insurance [Member] | Workers' Compensation, General and Automobile Policies [Member]
Loss Contingencies [Line Items]
Letters of credit issued	67.6	88.9
Surety Bonds [Member] | Self-Insurance [Member] | Workers' Compensation [Member]
Loss Contingencies [Line Items]
Outstanding bonds, amount	$ 34.8	$ 15.2

Commitments and Contingencies_2

Commitments and Contingencies (Investment Arrangements) (Narrative) (Details) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Other Commitments [Line Items]
Other current liabilities	$ 80,937	$ 65,455
Proportionately Consolidated Non-Controlled Joint Venture [Member] | Advances on Project Work [Member]
Other Commitments [Line Items]
Other current liabilities	$ 7,000
Proportionately Consolidated Non-Controlled Joint Venture [Member] | Pacer [Member]
Other Commitments [Line Items]
Proportionately consolidated non-controlled joint venture, ownership percentage	35.00%
Proportionately Consolidated Non-Controlled Joint Venture [Member] | 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%
Proportionately Consolidated Non-Controlled Joint Venture [Member] | 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_3

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_4

Commitments and Contingencies (Other Guarantees) (Narrative) (Details)	12 Months Ended
	Dec. 31, 2018
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.
Minimum [Member]
Other Guarantees [Line Items]
General warranty, period (in years)	1 year
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_5

Commitments and Contingencies (Concentrations of Risk) (Narrative) (Details) - customer	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Concentration Risk [Line Items]
Number of customers			470
Accounts Receivable, Net, Less BIEC [Member] | Credit Concentration Risk [Member] | Customers with Largest Net Accounts Receivable Positions [Member]
Concentration Risk [Line Items]
Number of customers	3	2
Accounts Receivable, Net, Less BIEC [Member] | Credit Concentration Risk [Member] | Customer with Largest Net Accounts Receivable Position [Member]
Concentration Risk [Line Items]
Concentration risk, percentage of total	26.00%	46.00%
Accounts Receivable, Net, Less BIEC [Member] | Credit Concentration Risk [Member] | Customer with Second Largest Net Accounts Receivable Position [Member]
Concentration Risk [Line Items]
Concentration risk, percentage of total	18.00%	15.00%
Accounts Receivable, Net, Less BIEC [Member] | Credit Concentration Risk [Member] | Customer With Third Highest Net Accounts Receivable Position [Member]
Concentration Risk [Line Items]
Concentration risk, percentage of total	12.00%
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			72.00%	78.00%	76.00%

Related Party Transactions (Man

Related Party Transactions (Management and Other Transactions) (Narrative) (Details) $ in Thousands	1 Months Ended	3 Months Ended	10 Months Ended	12 Months Ended
	Feb. 28, 2018USD ($)	Jun. 30, 2018USD ($)	Dec. 31, 2018USD ($)	Dec. 31, 2018USD ($)entity	Dec. 31, 2017USD ($)	Dec. 31, 2016USD ($)
Related Party Transaction [Line Items]
Payments of acquisition-related contingent consideration				$ 15,929	$ 6,676	$ 19,822
Management [Member] | 2017 Oil And Gas Acquisition [Member]
Related Party Transaction [Line Items]
Business combinations, cash paid (in dollars)					40,600
Contingent consideration, earn-out liability			$ 75,500	75,500
Payments of acquisition-related contingent consideration		$ 5,700
Management [Member] | Leases [Member]
Related Party Transaction [Line Items]
Payments, related party				46,900	46,800	43,300
Payables, related party			1,500	1,500	100
Management [Member] | Services [Member]
Related Party Transaction [Line Items]
Payments, related party				87,500	63,900	$ 27,700
Payables, related party			15,800	15,800	5,200
Management [Member] | Equipment [Member]
Related Party Transaction [Line Items]
Revenue, related party				900
Receivables, related party			200	200
Management [Member] | Construction Services [Member]
Related Party Transaction [Line Items]
Revenue, related party				$ 9,400	2,600
Number of entities | entity				2
Accounts receivable, net of BIEC, related parties			100	$ 100	$ 200
Immediate Family Member of Management [Member] | Construction Management Firm Specializing in Steel Building Systems [Member]
Related Party Transaction [Line Items]
Business combinations, cash paid (in dollars)	$ 6,100
Contingent consideration, earn-out liability			1,400	1,400
Business combinations, liabilities assumed, notes payable	$ 2,600
Notes payable, repayments			2,600
Financing or amounts advanced, related party				1,000
Advances outstanding from related party			$ 1,000	$ 1,000

Related Party Transactions (CCI

Related Party Transactions (CCI) (Narrative) (Details) - CCI [Member] - Immediate Family Member of Management [Member] - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Related Party Transaction [Line Items]
Equity investment, ownership percentage	15.00%
Equipment [Member]
Related Party Transaction [Line Items]
Payments, net of rebates, related party	$ 57.6	$ 54.9	$ 24.5
Payables, related party	4.9
Revenue, related party	0.3
Receivables, related party	$ 0.3

Related Party Transactions (Exe

Related Party Transactions (Executive Officers) (Narrative) (Details)	12 Months Ended
	Dec. 31, 2018USD ($)employee	Dec. 31, 2017USD ($)	Dec. 31, 2016USD ($)
Management [Member] | Subcontracting Arrangements [Member]
Related Party Transaction [Line Items]
Number of additional management employees, subcontracting arrangement | employee	2
Payments or amounts incurred, related party	$ 9,900,000	$ 78,000,000	$ 12,900,000
Payables, related party	400,000	2,000,000
Management [Member] | Equipment [Member]
Related Party Transaction [Line Items]
Proceeds from sale of equipment			300,000
Revenue, related party	900,000
Receivables, related party	200,000
Management [Member] | Services [Member]
Related Party Transaction [Line Items]
Payments or amounts incurred, related party	87,500,000	63,900,000	27,700,000
Payables, related party	15,800,000	5,200,000
Management [Member] | Leases [Member]
Related Party Transaction [Line Items]
Payments or amounts incurred, related party	46,900,000	46,800,000	43,300,000
Payables, related party	1,500,000	100,000
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	300,000	200,000
Executive Officers [Member] | Services [Member] | Related Customer [Member]
Related Party Transaction [Line Items]
Revenue, related party	900,000	800,000	900,000
Receivables, related party	300,000	300,000
Immediate Family Member of Management [Member] | Property Lease [Member]
Related Party Transaction [Line Items]
Payments or amounts incurred, related party	48,000	48,000	48,000
Chairman, Board of Directors [Member] | Leases [Member] | Aircraft [Member]
Related Party Transaction [Line Items]
Payments or amounts incurred, related party	$ 2,700,000	$ 2,000,000	$ 2,600,000

Related Party Transactions (Equ

Related Party Transactions (Equity Method Investment) (Narrative) (Details) - 2017 Acquisitions [Member] - USD ($)	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017
Financing Arrangements [Member]
Related Party Transaction [Line Items]
Payments, related party		$ 5,300,000
Payables, related party	$ 0
Equity Method Investee [Member]
Related Party Transaction [Line Items]
Equity method investment, ownership percentage	40.00%
Advances outstanding from related party, net		$ 300,000
Proceeds from settlement of advances, related party	$ 300,000

Related Party Transactions (Con

Related Party Transactions (Contractual Joint Venture) (Narrative) (Details) - Joint Venture [Member] - Pacer [Member] $ in Millions, $ in Millions	12 Months Ended
	Dec. 31, 2018USD ($)	Dec. 31, 2017USD ($)	Dec. 31, 2016USD ($)	Dec. 31, 2018CAD ($)	Dec. 31, 2017CAD ($)
Related Party Transaction [Line Items]
Proportionately consolidated non-controlled joint venture, ownership percentage	35.00%			35.00%
Performance Guarantees [Member]
Related Party Transaction [Line Items]
Guarantees issued, related party				$ 26.4	$ 132.1
Canadian Dollars [Member]
Related Party Transaction [Line Items]
Revenue, related party	$ 0.6	$ 1.5	$ 1
Accounts receivable, net of BIEC, related parties		0.8
Financing or amounts advanced, related party	2.7	7.2	$ 6.8
Canadian Dollars [Member] | Performance Guarantees [Member]
Related Party Transaction [Line Items]
Guarantees issued, related party	$ 19.4	$ 105.1

Related Party Transactions (Non

Related Party Transactions (Non-Controlling Interests) (Narrative) (Details) $ in Thousands	1 Months Ended	12 Months Ended
	Oct. 31, 2017USD ($)subsidiary	Dec. 31, 2018USD ($)	Dec. 31, 2017USD ($)	Dec. 31, 2016USD ($)
Related Party Transaction [Line Items]
Distributions to non-controlling interests		$ 559	$ 22,728	$ 0
Payments of acquisition-related contingent consideration		15,929	6,676	$ 19,822
Management [Member]
Related Party Transaction [Line Items]
Distributions to non-controlling interests		600	$ 1,300
Payments to acquire remaining non-controlling interests	$ 21,400
Management [Member] | Acquisition of Non-Controlling Interest [Member]
Related Party Transaction [Line Items]
Number of subsidiaries, non-controlling interests | subsidiary	1
Contingent consideration, earn-out liability		9,700
Payments of acquisition-related contingent consideration		$ 4,600

Related Party Transactions (Spl

Related Party Transactions (Split Dollar Agreements) (Narrative) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
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
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
Executive Officers [Member] | Other Long-Term Assets [Member]
Related Party Transaction [Line Items]
Life insurance assets, carrying amount	$ 18.5	$ 16.6

Quarterly Information (Unaudi_3

Quarterly Information (Unaudited) (Schedule of Quarterly Financial Information (Unaudited)) (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2018		Dec. 31, 2017		Dec. 31, 2016
Selected Quarterly Financial Information [Abstract]
Revenue	$ 1,917,600	$ 1,977,200	$ 1,617,800	$ 1,396,800	$ 1,602,900	$ 1,955,800	$ 1,890,200	$ 1,158,200	$ 6,909,417		$ 6,606,978		$ 5,134,703
Costs of revenue, excluding depreciation and amortization	1,654,000	1,681,400	1,366,600	1,237,300	1,421,700	1,726,200	1,626,300	971,100	5,939,308		5,745,307		4,442,125
Net income	31,800	120,500	80,400	26,500	160,700	64,200	83,300	40,600	259,231		348,884		134,035
Net income attributable to MasTec, Inc.	$ 31,900	$ 120,700	$ 80,500	$ 26,600	$ 160,800	$ 63,800	$ 81,700	$ 41,000	$ 259,659	[1]	$ 347,213	[1]	$ 131,263	[1]
Earnings per share:
Basic (in dollars per share)	$ 0.42	$ 1.55	$ 1.02	$ 0.33	$ 1.98	$ 0.79	$ 1.01	$ 0.51	$ 3.30		$ 4.29		$ 1.63
Diluted (in dollars per share)	$ 0.41	$ 1.52	$ 1.01	$ 0.32	$ 1.95	$ 0.77	$ 0.99	$ 0.50	$ 3.26		$ 4.22		$ 1.61
[1]	Calculated as total net income less amounts attributable to non-controlling interests.

Quarterly Information (Unaudi_4

Quarterly Information (Unaudited) (Narrative) (Details) - USD ($) $ in Thousands	3 Months Ended					12 Months Ended
	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Dec. 31, 2017	Mar. 31, 2017	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Quarterly Financial Information [Line Items]
Goodwill impairment	$ 47,700					$ 47,662	$ 0	$ 0
Stock based compensation, net excess tax benefits (in dollars)	1,300			$ 5,600		1,600	5,400	(100)
Change in tax rate, non-cash tax (expense) benefit	$ (3,700)	$ 17,900	$ (1,500)	$ 120,100		16,400	120,100
Joint Venture [Member] | Pacer [Member]
Quarterly Financial Information [Line Items]
Project gains			$ 1,000			$ 1,000
Project losses					$ 7,000		$ 7,900	$ 5,100

Supplemental Guarantor Financ_3

Supplemental Guarantor Financial Information (Narrative) (Details)	Dec. 31, 2018
Senior Notes [Member] | 4.875% Senior Notes [Member]
Condensed Financial Statements, Captions [Line Items]
Debt instrument, interest rate (percentage)	4.875%

Supplemental Guarantor Financ_4

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, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2018		Dec. 31, 2017		Dec. 31, 2016
Condensed Consolidating Statements of Operations and Comprehensive Income (Loss) [Line Items]
Revenue	$ 1,917,600	$ 1,977,200	$ 1,617,800	$ 1,396,800	$ 1,602,900	$ 1,955,800	$ 1,890,200	$ 1,158,200	$ 6,909,417		$ 6,606,978		$ 5,134,703
Costs of revenue, excluding depreciation and amortization	1,654,000	1,681,400	1,366,600	1,237,300	1,421,700	1,726,200	1,626,300	971,100	5,939,308		5,745,307		4,442,125
Depreciation and amortization									212,930		188,049		164,915
Goodwill impairment	47,700								47,662		0		0
General and administrative expenses									287,278		275,103		261,433
Interest expense (income), net									82,571		61,011		50,734
Equity in (earnings) losses of unconsolidated affiliates									(23,855)		(21,328)		(3,528)
Other (income) expense, net									(1,780)		(12,990)		(6,795)
Income before income taxes									365,303		371,826		225,819
(Provision for) benefit from income taxes									(106,072)		(22,942)		(91,784)
Net income (loss) before equity in income (loss) from subsidiaries									259,200		348,900		134,000
Equity in income (losses) from subsidiaries, net of tax									0		0		0
Net income	31,800	120,500	80,400	26,500	160,700	64,200	83,300	40,600	259,231		348,884		134,035
Net income (loss) attributable to non-controlling interests									(428)		1,671		2,772
Net income attributable to MasTec, Inc.	$ 31,900	$ 120,700	$ 80,500	$ 26,600	$ 160,800	$ 63,800	$ 81,700	$ 41,000	259,659	[1]	347,213	[1]	131,263	[1]
Comprehensive income (loss)									262,449		350,986		140,572
Reportable Legal Entities [Member] | MasTec, Inc. [Member]
Condensed Consolidating Statements of Operations and Comprehensive Income (Loss) [Line Items]
Revenue									0		0		0
Costs of revenue, excluding depreciation and amortization									0		0		0
Depreciation and amortization									0		0		0
Goodwill impairment									0
General and administrative expenses									3,100		2,300		2,400
Interest expense (income), net									0		0		0
Equity in (earnings) losses of unconsolidated affiliates									0		0		0
Other (income) expense, net									0		0		0
Income before income taxes									(3,100)		(2,300)		(2,400)
(Provision for) benefit from income taxes									900		200		900
Net income (loss) before equity in income (loss) from subsidiaries									(2,200)		(2,100)		(1,500)
Equity in income (losses) from subsidiaries, net of tax									261,900		349,300		132,800
Net income									259,700		347,200		131,300
Net income (loss) attributable to non-controlling interests									0		0		0
Net income attributable to MasTec, Inc.									259,700		347,200		131,300
Comprehensive income (loss)									262,900		349,300		137,800
Reportable Legal Entities [Member] | Guarantor Subsidiaries [Member]
Condensed Consolidating Statements of Operations and Comprehensive Income (Loss) [Line Items]
Revenue									6,539,300		6,222,300		4,790,900
Costs of revenue, excluding depreciation and amortization									5,609,400		5,378,600		4,101,200
Depreciation and amortization									190,500		159,100		134,200
Goodwill impairment									0
General and administrative expenses									266,400		256,300		234,400
Interest expense (income), net									147,000		123,600		112,000
Equity in (earnings) losses of unconsolidated affiliates									0		0		0
Other (income) expense, net									2,900		(13,000)		0
Income before income taxes									323,100		317,700		209,100
(Provision for) benefit from income taxes									(94,200)		(18,100)		(72,600)
Net income (loss) before equity in income (loss) from subsidiaries									228,900		299,600		136,500
Equity in income (losses) from subsidiaries, net of tax									0		0		0
Net income									228,900		299,600		136,500
Net income (loss) attributable to non-controlling interests									0		2,400		3,300
Net income attributable to MasTec, Inc.									228,900		297,200		133,200
Comprehensive income (loss)									228,900		299,600		136,500
Reportable Legal Entities [Member] | Non-Guarantor Subsidiaries [Member]
Condensed Consolidating Statements of Operations and Comprehensive Income (Loss) [Line Items]
Revenue									492,600		457,000		353,800
Costs of revenue, excluding depreciation and amortization									452,400		439,000		350,900
Depreciation and amortization									22,400		28,900		30,700
Goodwill impairment									47,700
General and administrative expenses									17,800		16,500		24,600
Interest expense (income), net									(64,400)		(62,600)		(61,300)
Equity in (earnings) losses of unconsolidated affiliates									(23,900)		(21,300)		(3,500)
Other (income) expense, net									(4,700)		0		(6,800)
Income before income taxes									45,300		56,500		19,200
(Provision for) benefit from income taxes									(12,800)		(5,000)		(20,100)
Net income (loss) before equity in income (loss) from subsidiaries									32,500		51,500		(900)
Equity in income (losses) from subsidiaries, net of tax									0		0		0
Net income									32,500		51,500		(900)
Net income (loss) attributable to non-controlling interests									(400)		(700)		(500)
Net income attributable to MasTec, Inc.									32,900		52,200		(400)
Comprehensive income (loss)									35,700		53,600		5,600
Eliminations [Member]
Condensed Consolidating Statements of Operations and Comprehensive Income (Loss) [Line Items]
Revenue									(122,500)		(72,300)		(10,000)
Costs of revenue, excluding depreciation and amortization									(122,500)		(72,300)		(10,000)
Depreciation and amortization									0		0		0
Goodwill impairment									0
General and administrative expenses									0		0		0
Interest expense (income), net									0		0		0
Equity in (earnings) losses of unconsolidated affiliates									0		0		0
Other (income) expense, net									0		0		0
Income before income taxes									0		0		0
(Provision for) benefit from income taxes									0		0		0
Net income (loss) before equity in income (loss) from subsidiaries									0		0		0
Equity in income (losses) from subsidiaries, net of tax									(261,900)		(349,300)		(132,800)
Net income									(261,900)		(349,300)		(132,800)
Net income (loss) attributable to non-controlling interests									0		0		0
Net income attributable to MasTec, Inc.									(261,900)		(349,300)		(132,800)
Comprehensive income (loss)									$ (265,100)		$ (351,400)		$ (139,300)
[1]	Calculated as total net income less amounts attributable to non-controlling interests.

Supplemental Guarantor Financ_5

Supplemental Guarantor Financial Information (Condensed Consolidating Balance Sheets) (Details) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Assets
Total current assets	$ 2,168,989	$ 1,852,366
Property and equipment, net	747,808	706,506
Goodwill and other intangible assets, net	1,269,700	1,328,900
Investments in and advances to consolidated affiliates, net	0	0
Other long-term assets	253,436	178,824
Total assets	4,439,953	4,066,576	$ 3,183,100
Liabilities and equity
Total current liabilities	1,283,611	963,827
Long-term debt	1,324,223	1,280,706
Other long-term liabilities	440,100	388,700
Total liabilities	3,047,929	2,633,223
Total equity	1,392,024	1,433,353	$ 1,103,634	$ 943,391
Total liabilities and equity	4,439,953	4,066,576
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	1,373,100	1,415,000
Other long-term assets	16,800	15,800
Total assets	1,389,900	1,430,800
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	1,389,900	1,430,800
Total liabilities and equity	1,389,900	1,430,800
Reportable Legal Entities [Member] | Guarantor Subsidiaries [Member]
Assets
Total current assets	1,993,000	1,536,600
Property and equipment, net	699,200	638,700
Goodwill and other intangible assets, net	1,188,000	1,187,900
Investments in and advances to consolidated affiliates, net	1,138,400	847,700
Other long-term assets	42,000	23,400
Total assets	5,060,600	4,234,300
Liabilities and equity
Total current liabilities	1,185,900	778,600
Long-term debt	1,319,400	1,269,400
Other long-term liabilities	429,200	379,900
Total liabilities	2,934,500	2,427,900
Total equity	2,126,100	1,806,400
Total liabilities and equity	5,060,600	4,234,300
Reportable Legal Entities [Member] | Non-Guarantor Subsidiaries [Member]
Assets
Total current assets	248,500	332,900
Property and equipment, net	48,600	67,800
Goodwill and other intangible assets, net	81,700	141,000
Investments in and advances to consolidated affiliates, net	816,900	746,600
Other long-term assets	194,600	139,600
Total assets	1,390,300	1,427,900
Liabilities and equity
Total current liabilities	170,200	202,300
Long-term debt	4,900	11,300
Other long-term liabilities	10,800	8,800
Total liabilities	185,900	222,400
Total equity	1,204,400	1,205,500
Total liabilities and equity	1,390,300	1,427,900
Eliminations [Member]
Assets
Total current assets	(72,500)	(17,100)
Property and equipment, net	0	0
Goodwill and other intangible assets, net	0	0
Investments in and advances to consolidated affiliates, net	(3,328,400)	(3,009,300)
Other long-term assets	0	0
Total assets	(3,400,900)	(3,026,400)
Liabilities and equity
Total current liabilities	(72,500)	(17,100)
Long-term debt	0	0
Other long-term liabilities	0	0
Total liabilities	(72,500)	(17,100)
Total equity	(3,328,400)	(3,009,300)
Total liabilities and equity	$ (3,400,900)	$ (3,026,400)

Supplemental Guarantor Financ_6

Supplemental Guarantor Financial Information (Condensed Consolidating Statements of Cash Flows) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Condensed Consolidating Statements of Cash Flows [Line Items]
Net cash provided by (used in) operating activities	$ 529,956	$ 144,096	$ 205,593
Cash flows from investing activities:
Cash paid for acquisitions, net of cash acquired	(6,684)	(115,995)	(4,102)
Capital expenditures	(180,420)	(123,412)	(117,114)
Proceeds from sale of property and equipment	39,359	19,963	11,239
Payments for other investments	(39,469)	(77,105)	(32,169)
Proceeds from other investments	5,415	23,801	1,125
Net cash used in investing activities	(181,799)	(272,748)	(141,021)
Cash flows from financing activities:
Proceeds from credit facilities	3,418,232	2,699,047	1,681,424
Repayments of credit facilities	(3,359,521)	(2,457,293)	(1,627,129)
Repayments of other borrowings and capital lease obligations, net	(89,600)	(71,100)	(68,700)
Payments of acquisition-related contingent consideration	(15,929)	(6,676)	(19,822)
Payments to non-controlling interests, including acquisition of interests and distributions	(559)	(22,728)	0
Proceeds from (payments for) stock-based awards, net	226	(3,085)	4,200
Repurchases of common stock	(313,949)	(1,552)	0
Other financing activities, net	0	(6,301)	515
Net financing activities and advances from (to) consolidated affiliates	0	0	0
Net cash (used in) provided by financing activities	(361,094)	130,322	(29,486)
Effect of currency translation on cash	33	(111)	(1,303)
Net (decrease) increase in cash and cash equivalents	(12,904)	1,559	33,783
Cash and cash equivalents - beginning of period	40,326	38,767	4,984
Cash and cash equivalents - end of period	27,422	40,326	38,767
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	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	0
Proceeds from (payments for) stock-based awards, net	200	(3,100)	4,200
Repurchases of common stock	(313,900)	(1,600)
Other financing activities, net	0	0	100
Net financing activities and advances from (to) consolidated affiliates	313,700	4,700	(4,300)
Net cash (used in) provided by financing activities	0	0	0
Effect of currency translation on cash	0	0	0
Net (decrease) increase 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	341,600	142,900	130,500
Cash flows from investing activities:
Cash paid for acquisitions, net of cash acquired	(6,700)	(116,000)	(4,100)
Capital expenditures	(174,300)	(120,100)	(112,600)
Proceeds from sale of property and equipment	26,200	18,200	7,600
Payments for other investments	(11,800)	(3,800)	(3,900)
Proceeds from other investments	0	1,200	0
Net cash used in investing activities	(166,600)	(220,500)	(113,000)
Cash flows from financing activities:
Proceeds from credit facilities	3,383,900	2,674,400	1,553,400
Repayments of credit facilities	(3,314,800)	(2,428,900)	(1,496,600)
Repayments of other borrowings and capital lease obligations, net	(83,700)	(61,500)	(50,400)
Payments of acquisition-related contingent consideration	(15,900)	(6,600)	(16,600)
Payments to non-controlling interests, including acquisition of interests and distributions	(600)	(22,700)
Proceeds from (payments for) stock-based awards, net	0	0	0
Repurchases of common stock	0	0
Other financing activities, net	0	(6,300)	400
Net financing activities and advances from (to) consolidated affiliates	(142,100)	(89,600)	16,400
Net cash (used in) provided by financing activities	(173,200)	58,800	6,600
Effect of currency translation on cash	0	0	0
Net (decrease) increase in cash and cash equivalents	1,800	(18,800)	24,100
Cash and cash equivalents - beginning of period	10,100	28,900	4,800
Cash and cash equivalents - end of period	11,900	10,100	28,900
Reportable Legal Entities [Member] | Non-Guarantor Subsidiaries [Member]
Condensed Consolidating Statements of Cash Flows [Line Items]
Net cash provided by (used in) operating activities	188,400	1,200	75,100
Cash flows from investing activities:
Cash paid for acquisitions, net of cash acquired	0	0	0
Capital expenditures	(6,100)	(3,300)	(4,500)
Proceeds from sale of property and equipment	13,100	1,800	3,600
Payments for other investments	(27,600)	(73,300)	(28,200)
Proceeds from other investments	5,400	22,600	1,100
Net cash used in investing activities	(15,200)	(52,200)	(28,000)
Cash flows from financing activities:
Proceeds from credit facilities	34,300	24,600	128,000
Repayments of credit facilities	(44,700)	(28,400)	(130,500)
Repayments of other borrowings and capital lease obligations, net	(5,900)	(9,600)	(18,300)
Payments of acquisition-related contingent consideration	0	0	(3,200)
Payments to non-controlling interests, including acquisition of interests and distributions	0	0
Proceeds from (payments for) stock-based awards, net	0	0	0
Repurchases of common stock	0	0
Other financing activities, net	0	0	0
Net financing activities and advances from (to) consolidated affiliates	(171,600)	84,900	(12,100)
Net cash (used in) provided by financing activities	(187,900)	71,500	(36,100)
Effect of currency translation on cash	0	(100)	(1,300)
Net (decrease) increase in cash and cash equivalents	(14,700)	20,400	9,700
Cash and cash equivalents - beginning of period	30,300	9,900	200
Cash and cash equivalents - end of period	15,600	30,300	9,900
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	0
Proceeds from (payments for) stock-based awards, net	0	0	0
Repurchases 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 (used in) provided by financing activities	0	0	0
Effect of currency translation on cash	0	0	0
Net (decrease) increase 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 Q_2

Schedule II - Valuation and Qualifying Accounts (Details) - USD ($) $ in Millions		12 Months Ended
		Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Schedule II - Valuation and Qualifying Accounts [Roll Forward]
Balance at beginning of period		$ 83.6	$ 42.8	$ 28
Charges to cost and expense		42.8	50.2	24.6
Other additions		0	0	1
(Deductions)		(39.7)	(9.4)	(10.8)
Balance at end of period		86.7	83.6	42.8
Allowance for Doubtful Accounts [Member]
Schedule II - Valuation and Qualifying Accounts [Roll Forward]
Balance at beginning of period		8.2	8.4	7.7
Charges to cost and expense	[1]	8.6	2.6	2.9
Other additions		0	0	0
(Deductions)	[2]	(0.5)	(2.8)	(2.2)
Balance at end of period		16.3	8.2	8.4
Costs and Earnings in Excess of Billings Allowance [Member]
Schedule II - Valuation and Qualifying Accounts [Roll Forward]
Balance at beginning of period		27.2	9.5	6.9
Charges to cost and expense	[1]	33	22.3	9.9
Other additions		0	0	0
(Deductions)	[2]	(38.2)	(4.6)	(7.3)
Balance at end of period		22	27.2	9.5
Valuation Allowance for Inventory [Member]
Schedule II - Valuation and Qualifying Accounts [Roll Forward]
Balance at beginning of period		7.7	3.5	2.8
Charges to cost and expense	[3]	1.1	6.2	2
Other additions		0	0	0
(Deductions)	[4]	(1)	(2)	(1.3)
Balance at end of period		7.8	7.7	3.5
Valuation Allowance for Deferred Tax Assets [Member]
Schedule II - Valuation and Qualifying Accounts [Roll Forward]
Balance at beginning of period		40.5	21.4	10.6
Charges to cost and expense	[5]	0.1	19.1	9.8
Other additions		0	0	1	[6]
(Deductions)		0	0	0
Balance at end of period		$ 40.6	$ 40.5	$ 21.4
[1]	Provisions for doubtful accounts and costs and earnings in excess of billings.
[2]	Write-offs and reversals of uncollectible accounts receivable and non-billable costs and earnings in excess of billings.
[3]	Provisions for obsolete inventory and other adjustments to net realizable value.
[4]	Inventory write-offs.
[5]	Additions related to federal, foreign, and state attributes.
[6]	Additions related to unrealized gains and losses.