Supplemental Guarantor Financial Information (Condensed Unaudited Consolidating Statements of Operations and Comprehensive Income (Loss)) (Details) - USD ($) $ in Thousands		3 Months Ended
		Mar. 31, 2019	Mar. 31, 2018
Condensed Unaudited Consolidating Statements of Operations and Comprehensive Income (Loss) [Line Items]
Revenue		$ 1,518,340	$ 1,396,834
Costs of revenue, excluding depreciation and amortization		1,312,048	1,237,299
Depreciation and amortization		59,031	49,940
General and administrative expenses		72,616	63,622
Interest expense (income), net		22,258	17,058
Equity in earnings of unconsolidated affiliates		(6,260)	(5,585)
Other expense (income), net		3,507	(3,089)
Income before income taxes		55,140	37,589
(Provision for) benefit from income taxes		(12,033)	(11,126)
Net income (loss) before equity in income from subsidiaries		43,100	26,500
Equity in income (losses) from subsidiaries, net of tax		0	0
Net income		43,107	26,463
Net loss attributable to non-controlling interests		(5)	(97)
Net income attributable to MasTec, Inc.	[1]	43,112	26,560
Comprehensive income (loss)		37,545	33,656
Reportable Legal Entities [Member] | MasTec, Inc. [Member]
Condensed Unaudited Consolidating Statements of Operations and Comprehensive Income (Loss) [Line Items]
Revenue		0	0
Costs of revenue, excluding depreciation and amortization		0	0
Depreciation and amortization		0	0
General and administrative expenses		800	800
Interest expense (income), net		0	0
Equity in earnings of unconsolidated affiliates		0	0
Other expense (income), net		0	0
Income before income taxes		(800)	(800)
(Provision for) benefit from income taxes		300	200
Net income (loss) before equity in income from subsidiaries		(500)	(600)
Equity in income (losses) from subsidiaries, net of tax		43,700	27,100
Net income		43,200	26,500
Net loss attributable to non-controlling interests		0	0
Net income attributable to MasTec, Inc.		43,200	26,500
Comprehensive income (loss)		37,500	33,800
Reportable Legal Entities [Member] | Guarantor Subsidiaries [Member]
Condensed Unaudited Consolidating Statements of Operations and Comprehensive Income (Loss) [Line Items]
Revenue		1,402,400	1,265,600
Costs of revenue, excluding depreciation and amortization		1,200,700	1,136,200
Depreciation and amortization		54,700	43,300
General and administrative expenses		67,300	59,200
Interest expense (income), net		37,700	32,900
Equity in earnings of unconsolidated affiliates		100	0
Other expense (income), net		5,000	(2,600)
Income before income taxes		36,900	(3,400)
(Provision for) benefit from income taxes		(12,000)	800
Net income (loss) before equity in income from subsidiaries		24,900	(2,600)
Equity in income (losses) from subsidiaries, net of tax		0	0
Net income		24,900	(2,600)
Net loss attributable to non-controlling interests		0	0
Net income attributable to MasTec, Inc.		24,900	(2,600)
Comprehensive income (loss)		24,900	(2,600)
Reportable Legal Entities [Member] | Non-Guarantor Subsidiaries [Member]
Condensed Unaudited Consolidating Statements of Operations and Comprehensive Income (Loss) [Line Items]
Revenue		139,100	185,600
Costs of revenue, excluding depreciation and amortization		134,500	155,500
Depreciation and amortization		4,300	6,600
General and administrative expenses		4,500	3,600
Interest expense (income), net		(15,400)	(15,800)
Equity in earnings of unconsolidated affiliates		(6,300)	(5,600)
Other expense (income), net		(1,500)	(500)
Income before income taxes		19,000	41,800
(Provision for) benefit from income taxes		(300)	(12,100)
Net income (loss) before equity in income from subsidiaries		18,700	29,700
Equity in income (losses) from subsidiaries, net of tax		0	0
Net income		18,700	29,700
Net loss attributable to non-controlling interests		0	(100)
Net income attributable to MasTec, Inc.		18,700	29,800
Comprehensive income (loss)		13,200	36,800
Eliminations [Member]
Condensed Unaudited Consolidating Statements of Operations and Comprehensive Income (Loss) [Line Items]
Revenue		(23,200)	(54,400)
Costs of revenue, excluding depreciation and amortization		(23,200)	(54,400)
Depreciation and amortization		0	0
General and administrative expenses		0	0
Interest expense (income), net		0	0
Equity in earnings of unconsolidated affiliates		0	0
Other expense (income), net		0	0
Income before income taxes		0	0
(Provision for) benefit from income taxes		0	0
Net income (loss) before equity in income from subsidiaries		0	0
Equity in income (losses) from subsidiaries, net of tax		(43,700)	(27,100)
Net income		(43,700)	(27,100)
Net loss attributable to non-controlling interests		0	0
Net income attributable to MasTec, Inc.		(43,700)	(27,100)
Comprehensive income (loss)		$ (38,100)	$ (34,300)

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