Supplemental Guarantor Financial Information (Condensed Unaudited Consolidating Statements of Operations and Comprehensive Income (Loss)) (Details) - USD ($) $ in Thousands		3 Months Ended		6 Months Ended
		Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Condensed Unaudited Consolidating Statements of Operations and Comprehensive Income (Loss) [Line Items]
Revenue		$ 1,617,804	$ 1,890,180	$ 3,014,638	$ 3,048,364
Costs of revenue, excluding depreciation and amortization		1,366,584	1,626,335	2,603,883	2,597,469
Depreciation and amortization		51,676	45,379	101,615	88,282
General and administrative expenses		67,602	70,823	131,224	135,604
Interest expense (income), net		20,795	14,791	37,854	27,388
Equity in earnings of unconsolidated affiliates		(5,824)	(6,060)	(11,409)	(7,706)
Other expense (income), net		788	146	(2,301)	576
Income before income taxes		116,183	138,766	153,772	206,751
(Provision for) benefit from income taxes		(35,782)	(55,434)	(46,908)	(82,792)
Net income (loss) before equity in income from subsidiaries		80,400	83,300	106,900	124,000
Equity in income (losses) from subsidiaries, net of tax		0	0	0	0
Net income		80,401	83,332	106,864	123,959
Net (loss) income attributable to non-controlling interests		(91)	1,664	(188)	1,321
Net income attributable to MasTec, Inc.	[1]	80,492	81,668	107,052	122,638
Comprehensive income (loss)		81,686	81,197	115,342	123,638
Reportable Legal Entities [Member] | MasTec, Inc. [Member]
Condensed Unaudited Consolidating Statements of Operations and Comprehensive Income (Loss) [Line Items]
Revenue		0	0	0	0
Costs of revenue, excluding depreciation and amortization		0	0	0	0
Depreciation and amortization		0	0	0	0
General and administrative expenses		800	600	1,500	1,200
Interest expense (income), net		0	0	0	0
Equity in earnings of unconsolidated affiliates		0	0	0	0
Other expense (income), net		0	0	0	0
Income before income taxes		(800)	(600)	(1,500)	(1,200)
(Provision for) benefit from income taxes		200	200	400	400
Net income (loss) before equity in income from subsidiaries		(600)	(400)	(1,100)	(800)
Equity in income (losses) from subsidiaries, net of tax		81,100	82,100	108,200	123,400
Net income		80,500	81,700	107,100	122,600
Net (loss) income attributable to non-controlling interests		0	0	0	0
Net income attributable to MasTec, Inc.		80,500	81,700	107,100	122,600
Comprehensive income (loss)		81,800	79,500	115,500	122,300
Reportable Legal Entities [Member] | Guarantor Subsidiaries [Member]
Condensed Unaudited Consolidating Statements of Operations and Comprehensive Income (Loss) [Line Items]
Revenue		1,556,900	1,820,000	2,822,500	2,903,200
Costs of revenue, excluding depreciation and amortization		1,309,100	1,557,900	2,445,300	2,446,500
Depreciation and amortization		46,200	38,200	89,500	73,500
General and administrative expenses		63,100	66,700	122,400	126,400
Interest expense (income), net		37,100	30,500	70,000	58,400
Equity in earnings of unconsolidated affiliates		0	0	0	0
Other expense (income), net		1,200	(5,300)	(1,400)	(5,300)
Income before income taxes		100,200	132,000	96,700	203,700
(Provision for) benefit from income taxes		(25,900)	(47,900)	(24,900)	(74,200)
Net income (loss) before equity in income from subsidiaries		74,300	84,100	71,800	129,500
Equity in income (losses) from subsidiaries, net of tax		0	0	0	0
Net income		74,300	84,100	71,800	129,500
Net (loss) income attributable to non-controlling interests		0	1,800	0	1,600
Net income attributable to MasTec, Inc.		74,300	82,300	71,800	127,900
Comprehensive income (loss)		74,300	84,100	71,800	129,500
Reportable Legal Entities [Member] | Non-Guarantor Subsidiaries [Member]
Condensed Unaudited Consolidating Statements of Operations and Comprehensive Income (Loss) [Line Items]
Revenue		84,000	85,500	269,600	173,400
Costs of revenue, excluding depreciation and amortization		80,600	83,700	236,100	179,200
Depreciation and amortization		5,500	7,200	12,100	14,800
General and administrative expenses		3,700	3,500	7,300	8,000
Interest expense (income), net		(16,300)	(15,700)	(32,100)	(31,000)
Equity in earnings of unconsolidated affiliates		(5,800)	(6,100)	(11,400)	(7,700)
Other expense (income), net		(400)	5,500	(900)	5,900
Income before income taxes		16,700	7,400	58,500	4,200
(Provision for) benefit from income taxes		(10,100)	(7,700)	(22,300)	(9,000)
Net income (loss) before equity in income from subsidiaries		6,600	(300)	36,200	(4,800)
Equity in income (losses) from subsidiaries, net of tax		0	0	0	0
Net income		6,600	(300)	36,200	(4,800)
Net (loss) income attributable to non-controlling interests		(100)	(100)	(200)	(300)
Net income attributable to MasTec, Inc.		6,700	(200)	36,400	(4,500)
Comprehensive income (loss)		8,000	(2,500)	44,700	(5,100)
Eliminations [Member]
Condensed Unaudited Consolidating Statements of Operations and Comprehensive Income (Loss) [Line Items]
Revenue		(23,100)	(15,300)	(77,500)	(28,200)
Costs of revenue, excluding depreciation and amortization		(23,100)	(15,300)	(77,500)	(28,200)
Depreciation and amortization		0	0	0	0
General and administrative expenses		0	0	0	0
Interest expense (income), net		0	0	0	0
Equity in earnings of unconsolidated affiliates		0	0	0	0
Other expense (income), net		0	0	0	0
Income before income taxes		0	0	0	0
(Provision for) benefit from income taxes		0	0	0	0
Net income (loss) before equity in income from subsidiaries		0	0	0	0
Equity in income (losses) from subsidiaries, net of tax		(81,100)	(82,100)	(108,200)	(123,400)
Net income		(81,100)	(82,100)	(108,200)	(123,400)
Net (loss) income attributable to non-controlling interests		0	0	0	0
Net income attributable to MasTec, Inc.		(81,100)	(82,100)	(108,200)	(123,400)
Comprehensive income (loss)		$ (82,400)	$ (79,900)	$ (116,700)	$ (123,100)

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