Supplemental Guarantor Financial Information (Condensed Unaudited Consolidating Statements of Operations and Comprehensive Income (Loss)) (Details) - USD ($) $ in Thousands		3 Months Ended		9 Months Ended
		Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Condensed Unaudited Consolidating Statements of Operations and Comprehensive Income (Loss) [Line Items]
Revenue		$ 1,977,227	$ 1,955,752	$ 4,991,865	$ 5,004,116
Costs of revenue, excluding depreciation and amortization		1,681,438	1,726,173	4,285,320	4,323,642
Depreciation and amortization		54,863	50,101	156,478	138,384
General and administrative expenses		80,311	66,397	211,535	202,001
Interest expense (income), net		22,330	17,578	60,183	44,966
Equity in earnings of unconsolidated affiliates		(7,671)	(7,399)	(19,080)	(15,105)
Other expense (income), net		323	(4,677)	(1,976)	(4,102)
Income before income taxes		145,633	107,579	299,405	314,330
(Provision for) benefit from income taxes		(25,091)	(43,378)	(71,999)	(126,170)
Net income (loss) before equity in income from subsidiaries		120,500	64,200	227,400	188,200
Equity in income (losses) from subsidiaries, net of tax		0	0	0	0
Net income		120,542	64,201	227,406	188,160
Net (loss) income attributable to non-controlling interests		(124)	449	(312)	1,770
Net income attributable to MasTec, Inc.	[1]	120,666	63,752	227,718	186,390
Comprehensive income (loss)		124,909	65,650	240,251	189,288
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		700	500	2,300	1,700
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		(700)	(500)	(2,300)	(1,700)
(Provision for) benefit from income taxes		200	200	600	600
Net income (loss) before equity in income from subsidiaries		(500)	(300)	(1,700)	(1,100)
Equity in income (losses) from subsidiaries, net of tax		121,200	64,000	229,400	187,500
Net income		120,700	63,700	227,700	186,400
Net (loss) income attributable to non-controlling interests		0	0	0	0
Net income attributable to MasTec, Inc.		120,700	63,700	227,700	186,400
Comprehensive income (loss)		124,900	65,200	240,600	187,500
Reportable Legal Entities [Member] | Guarantor Subsidiaries [Member]
Condensed Unaudited Consolidating Statements of Operations and Comprehensive Income (Loss) [Line Items]
Revenue		1,894,500	1,860,300	4,717,000	4,763,400
Costs of revenue, excluding depreciation and amortization		1,603,000	1,634,500	4,048,200	4,081,100
Depreciation and amortization		49,700	42,700	139,200	116,200
General and administrative expenses		73,200	62,000	195,600	188,400
Interest expense (income), net		38,700	33,300	108,700	91,600
Equity in earnings of unconsolidated affiliates		0	0	0	0
Other expense (income), net		2,100	(4,600)	800	(10,000)
Income before income taxes		127,800	92,400	224,500	296,100
(Provision for) benefit from income taxes		(35,900)	(35,100)	(60,900)	(109,300)
Net income (loss) before equity in income from subsidiaries		91,900	57,300	163,600	186,800
Equity in income (losses) from subsidiaries, net of tax		0	0	0	0
Net income		91,900	57,300	163,600	186,800
Net (loss) income attributable to non-controlling interests		0	800	0	2,400
Net income attributable to MasTec, Inc.		91,900	56,500	163,600	184,400
Comprehensive income (loss)		91,900	57,300	163,600	186,800
Reportable Legal Entities [Member] | Non-Guarantor Subsidiaries [Member]
Condensed Unaudited Consolidating Statements of Operations and Comprehensive Income (Loss) [Line Items]
Revenue		102,300	105,400	372,000	278,800
Costs of revenue, excluding depreciation and amortization		98,000	101,600	334,200	280,600
Depreciation and amortization		5,200	7,400	17,300	22,200
General and administrative expenses		6,400	3,900	13,600	11,900
Interest expense (income), net		(16,400)	(15,700)	(48,500)	(46,600)
Equity in earnings of unconsolidated affiliates		(7,700)	(7,400)	(19,100)	(15,100)
Other expense (income), net		(1,800)	(100)	(2,800)	5,900
Income before income taxes		18,600	15,700	77,300	19,900
(Provision for) benefit from income taxes		10,600	(8,500)	(11,700)	(17,500)
Net income (loss) before equity in income from subsidiaries		29,200	7,200	65,600	2,400
Equity in income (losses) from subsidiaries, net of tax		0	0	0	0
Net income		29,200	7,200	65,600	2,400
Net (loss) income attributable to non-controlling interests		(100)	(300)	(300)	(600)
Net income attributable to MasTec, Inc.		29,300	7,500	65,900	3,000
Comprehensive income (loss)		33,600	8,700	78,300	3,600
Eliminations [Member]
Condensed Unaudited Consolidating Statements of Operations and Comprehensive Income (Loss) [Line Items]
Revenue		(19,600)	(9,900)	(97,100)	(38,100)
Costs of revenue, excluding depreciation and amortization		(19,600)	(9,900)	(97,100)	(38,100)
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		(121,200)	(64,000)	(229,400)	(187,500)
Net income		(121,200)	(64,000)	(229,400)	(187,500)
Net (loss) income attributable to non-controlling interests		0	0	0	0
Net income attributable to MasTec, Inc.		(121,200)	(64,000)	(229,400)	(187,500)
Comprehensive income (loss)		$ (125,500)	$ (65,500)	$ (242,200)	$ (188,600)

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