Supplemental Guarantor Financial Information (Condensed Consolidating Statements of Operations and Comprehensive Income (Loss) (Unaudited)) (Details) - USD ($) $ in Thousands		3 Months Ended		9 Months Ended
		Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Condensed Unaudited Consolidating Statements of Operations and Comprehensive Income (Loss) [Line Items]
Revenue		$ 2,016,618	$ 1,977,227	$ 5,473,965	$ 4,991,865
Costs of revenue, excluding depreciation and amortization		1,690,558	1,681,438	4,636,006	4,285,320
Depreciation and amortization		55,196	54,863	174,171	156,478
General and administrative expenses		77,146	80,311	220,581	211,535
Interest expense (income), net		19,297	22,330	58,178	60,183
Equity in earnings of unconsolidated affiliates		(6,966)	(7,671)	(19,778)	(19,080)
Other expense (income), net		8,002	323	16,323	(1,976)
Income before income taxes		173,385	145,633	388,484	299,405
(Provision for) benefit from income taxes		(43,303)	(25,091)	(95,073)	(71,999)
Net income (loss) before equity in income from subsidiaries		130,100	120,500	293,400	227,400
Equity in income (losses) from subsidiaries, net of tax		0	0	0	0
Net income		130,082	120,542	293,411	227,406
Net income (loss) attributable to non-controlling interests		1,486	(124)	1,993	(312)
Net income attributable to MasTec, Inc.	[1]	128,596	120,666	291,418	227,718
Comprehensive income (loss)		122,640	124,909	271,788	240,251
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	700	2,300	2,300
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)	(700)	(2,300)	(2,300)
(Provision for) benefit from income taxes		200	200	700	600
Net income (loss) before equity in income from subsidiaries		(600)	(500)	(1,600)	(1,700)
Equity in income (losses) from subsidiaries, net of tax		129,200	121,200	293,000	229,400
Net income		128,600	120,700	291,400	227,700
Net income (loss) attributable to non-controlling interests		0	0	0	0
Net income attributable to MasTec, Inc.		128,600	120,700	291,400	227,700
Comprehensive income (loss)		121,200	124,900	269,800	240,600
Reportable Legal Entities [Member] | Guarantor Subsidiaries [Member]
Condensed Unaudited Consolidating Statements of Operations and Comprehensive Income (Loss) [Line Items]
Revenue		1,916,800	1,894,500	5,164,000	4,717,000
Costs of revenue, excluding depreciation and amortization		1,609,200	1,603,000	4,354,700	4,048,200
Depreciation and amortization		51,800	49,700	161,700	139,200
General and administrative expenses		72,200	73,200	205,600	195,600
Interest expense (income), net		35,400	38,700	105,600	108,700
Equity in earnings of unconsolidated affiliates		0	0	100	0
Other expense (income), net		8,600	2,100	53,900	800
Income before income taxes		139,600	127,800	282,400	224,500
(Provision for) benefit from income taxes		(39,100)	(35,900)	(90,100)	(60,900)
Net income (loss) before equity in income from subsidiaries		100,500	91,900	192,300	163,600
Equity in income (losses) from subsidiaries, net of tax		0	0	0	0
Net income		100,500	91,900	192,300	163,600
Net income (loss) attributable to non-controlling interests		0	0	0	0
Net income attributable to MasTec, Inc.		100,500	91,900	192,300	163,600
Comprehensive income (loss)		100,500	91,900	192,300	163,600
Reportable Legal Entities [Member] | Non-Guarantor Subsidiaries [Member]
Condensed Unaudited Consolidating Statements of Operations and Comprehensive Income (Loss) [Line Items]
Revenue		126,400	102,300	388,900	372,000
Costs of revenue, excluding depreciation and amortization		108,000	98,000	360,200	334,200
Depreciation and amortization		3,400	5,200	12,500	17,300
General and administrative expenses		4,100	6,400	12,700	13,600
Interest expense (income), net		(16,100)	(16,400)	(47,400)	(48,500)
Equity in earnings of unconsolidated affiliates		(7,000)	(7,700)	(19,900)	(19,100)
Other expense (income), net		(600)	(1,800)	(37,600)	(2,800)
Income before income taxes		34,600	18,600	108,400	77,300
(Provision for) benefit from income taxes		(4,400)	10,600	(5,700)	(11,700)
Net income (loss) before equity in income from subsidiaries		30,200	29,200	102,700	65,600
Equity in income (losses) from subsidiaries, net of tax		0	0	0	0
Net income		30,200	29,200	102,700	65,600
Net income (loss) attributable to non-controlling interests		1,500	(100)	2,000	(300)
Net income attributable to MasTec, Inc.		28,700	29,300	100,700	65,900
Comprehensive income (loss)		22,700	33,600	81,100	78,300
Eliminations [Member]
Condensed Unaudited Consolidating Statements of Operations and Comprehensive Income (Loss) [Line Items]
Revenue		(26,600)	(19,600)	(78,900)	(97,100)
Costs of revenue, excluding depreciation and amortization		(26,600)	(19,600)	(78,900)	(97,100)
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		(129,200)	(121,200)	(293,000)	(229,400)
Net income		(129,200)	(121,200)	(293,000)	(229,400)
Net income (loss) attributable to non-controlling interests		0	0	0	0
Net income attributable to MasTec, Inc.		(129,200)	(121,200)	(293,000)	(229,400)
Comprehensive income (loss)		$ (121,700)	$ (125,500)	$ (271,400)	$ (242,200)

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