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, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2017		Dec. 31, 2016		Dec. 31, 2015
Condensed Consolidating Statements of Operations and Comprehensive Income (Loss) [Line Items]
Revenue	$ 1,602,900	$ 1,955,800	$ 1,890,200	$ 1,158,200	$ 1,341,900	$ 1,586,200	$ 1,232,400	$ 974,200	$ 6,606,978		$ 5,134,703		$ 4,208,330
Costs of revenue, excluding depreciation and amortization	1,421,700	1,726,200	1,626,300	971,100	1,120,600	1,369,000	1,068,200	884,400	5,745,307		4,442,125		3,721,303
Depreciation and amortization									188,049		164,915		169,662
Goodwill and intangible asset impairment									0		0		78,625
General and administrative expenses									275,103		261,433		265,910
Interest expense (income), net									61,011		50,734		48,055
Equity in (earnings) losses of unconsolidated affiliates									(21,328)		(3,528)		7,978
Other (income) expense, net									(12,990)		(6,795)		(15,457)
Income (loss) before income taxes									371,826		225,819		(67,746)
(Provision for) benefit from income taxes									(22,942)		(91,784)		(11,957)
Net income (loss) before equity in income (loss) from subsidiaries									348,900		134,000		(79,700)
Equity in income (losses) from subsidiaries, net of tax									0		0		0
Net income (loss)	160,700	64,200	83,300	40,600	55,900	56,500	24,400	(2,900)	348,884		134,035		(79,703)
Net income (loss) attributable to non-controlling interests									1,671		2,772		(593)
Net income (loss) attributable to MasTec, Inc.	$ 160,800	$ 63,800	$ 81,700	$ 41,000	$ 53,600	$ 56,300	$ 24,100	$ (2,700)	347,213	[1]	131,263	[1]	(79,110)	[1]
Comprehensive income (loss)									350,986		140,572		(118,050)
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 and intangible asset impairment													0
General and administrative expenses									2,300		2,400		2,100
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 (loss) before income taxes									(2,300)		(2,400)		(2,100)
(Provision for) benefit from income taxes									200		900		1,100
Net income (loss) before equity in income (loss) from subsidiaries									(2,100)		(1,500)		(1,000)
Equity in income (losses) from subsidiaries, net of tax									349,300		132,800		(78,100)
Net income (loss)									347,200		131,300		(79,100)
Net income (loss) attributable to non-controlling interests									0		0		0
Net income (loss) attributable to MasTec, Inc.									347,200		131,300		(79,100)
Comprehensive income (loss)									349,300		137,800		(117,500)
Reportable Legal Entities [Member] | Guarantor Subsidiaries [Member]
Condensed Consolidating Statements of Operations and Comprehensive Income (Loss) [Line Items]
Revenue									6,222,300		4,790,900		3,527,000
Costs of revenue, excluding depreciation and amortization									5,378,600		4,101,200		3,073,600
Depreciation and amortization									159,100		134,200		130,600
Goodwill and intangible asset impairment													0
General and administrative expenses									256,300		234,400		235,400
Interest expense (income), net									123,600		112,000		111,000
Equity in (earnings) losses of unconsolidated affiliates									0		0		0
Other (income) expense, net									(13,000)		0		(6,200)
Income (loss) before income taxes									317,700		209,100		(17,400)
(Provision for) benefit from income taxes									(18,100)		(72,600)		9,300
Net income (loss) before equity in income (loss) from subsidiaries									299,600		136,500		(8,100)
Equity in income (losses) from subsidiaries, net of tax									0		0		0
Net income (loss)									299,600		136,500		(8,100)
Net income (loss) attributable to non-controlling interests									2,400		3,300		0
Net income (loss) attributable to MasTec, Inc.									297,200		133,200		(8,100)
Comprehensive income (loss)									299,600		136,500		(8,100)
Reportable Legal Entities [Member] | Non-Guarantor Subsidiaries [Member]
Condensed Consolidating Statements of Operations and Comprehensive Income (Loss) [Line Items]
Revenue									457,000		353,800		689,700
Costs of revenue, excluding depreciation and amortization									439,000		350,900		656,100
Depreciation and amortization									28,900		30,700		39,100
Goodwill and intangible asset impairment													78,600
General and administrative expenses									16,500		24,600		28,400
Interest expense (income), net									(62,600)		(61,300)		(62,900)
Equity in (earnings) losses of unconsolidated affiliates									(21,300)		(3,500)		8,000
Other (income) expense, net									0		(6,800)		(9,300)
Income (loss) before income taxes									56,500		19,200		(48,300)
(Provision for) benefit from income taxes									(5,000)		(20,100)		(22,300)
Net income (loss) before equity in income (loss) from subsidiaries									51,500		(900)		(70,600)
Equity in income (losses) from subsidiaries, net of tax									0		0		0
Net income (loss)									51,500		(900)		(70,600)
Net income (loss) attributable to non-controlling interests									(700)		(500)		(600)
Net income (loss) attributable to MasTec, Inc.									52,200		(400)		(70,000)
Comprehensive income (loss)									53,600		5,600		(109,000)
Eliminations [Member]
Condensed Consolidating Statements of Operations and Comprehensive Income (Loss) [Line Items]
Revenue									(72,300)		(10,000)		(8,400)
Costs of revenue, excluding depreciation and amortization									(72,300)		(10,000)		(8,400)
Depreciation and amortization									0		0		0
Goodwill and intangible asset 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 (loss) 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									(349,300)		(132,800)		78,100
Net income (loss)									(349,300)		(132,800)		78,100
Net income (loss) attributable to non-controlling interests									0		0		0
Net income (loss) attributable to MasTec, Inc.									(349,300)		(132,800)		78,100
Comprehensive income (loss)									$ (351,400)		$ (139,300)		$ 116,500

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