Supplemental Guarantor Financial Information (Condensed Consolidating Statements of Operations and Comprehensive Income (Loss) (Unaudited)) (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Condensed Unaudited Consolidating Statements of Operations and Comprehensive Income (Loss) [Line Items]
Revenue	$ 1,416,604	$ 1,518,340
Costs of revenue, excluding depreciation and amortization	1,226,297	1,312,048
Depreciation and amortization	60,500	59,000
General and administrative expenses	85,514	72,616
Interest expense (income), net	17,004	22,258
Equity in losses (earnings) of unconsolidated affiliates	7,834	6,260
Other expense (income), net	(1,342)	3,507
Income before income taxes	36,485	55,140
Benefit from (provision for) income taxes	(423)	(12,033)
Net income (loss) before equity in income from subsidiaries	36,100	43,100
Equity in income from subsidiaries, net of tax	0	0
Net income	36,062	43,107
Net loss attributable to non-controlling interests	(168)	(5)
Net income attributable to MasTec, Inc.	36,230	43,112
Comprehensive income (loss)	12,805	37,545
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	1,000	800
Interest expense (income), net	0	0
Equity in losses (earnings) of unconsolidated affiliates	0	0
Other expense (income), net	0	0
Income before income taxes	(1,000)	(800)
Benefit from (provision for) income taxes	300	300
Net income (loss) before equity in income from subsidiaries	(700)	(500)
Equity in income from subsidiaries, net of tax	36,900	43,700
Net income	36,200	43,200
Net loss attributable to non-controlling interests	0	0
Net income attributable to MasTec, Inc.	36,200	43,200
Comprehensive income (loss)	13,000	37,500
Reportable Legal Entities [Member] | Guarantor Subsidiaries [Member]
Condensed Unaudited Consolidating Statements of Operations and Comprehensive Income (Loss) [Line Items]
Revenue	1,312,300	1,402,400
Costs of revenue, excluding depreciation and amortization	1,138,800	1,200,700
Depreciation and amortization	54,200	54,700
General and administrative expenses	73,900	67,300
Interest expense (income), net	15,800	37,700
Equity in losses (earnings) of unconsolidated affiliates	200	(100)
Other expense (income), net	(1,100)	5,000
Income before income taxes	30,900	36,900
Benefit from (provision for) income taxes	(10,000)	(12,000)
Net income (loss) before equity in income from subsidiaries	20,900	24,900
Equity in income from subsidiaries, net of tax	0	0
Net income	20,900	24,900
Net loss attributable to non-controlling interests	0	0
Net income attributable to MasTec, Inc.	20,900	24,900
Comprehensive income (loss)	17,500	24,900
Reportable Legal Entities [Member] | Non-Guarantor Subsidiaries [Member]
Condensed Unaudited Consolidating Statements of Operations and Comprehensive Income (Loss) [Line Items]
Revenue	111,800	139,100
Costs of revenue, excluding depreciation and amortization	95,000	134,500
Depreciation and amortization	6,300	4,300
General and administrative expenses	10,600	4,500
Interest expense (income), net	1,200	(15,400)
Equity in losses (earnings) of unconsolidated affiliates	7,600	6,300
Other expense (income), net	(200)	(1,500)
Income before income taxes	6,500	19,000
Benefit from (provision for) income taxes	9,300	(300)
Net income (loss) before equity in income from subsidiaries	15,800	18,700
Equity in income from subsidiaries, net of tax	0	0
Net income	15,800	18,700
Net loss attributable to non-controlling interests	(200)	0
Net income attributable to MasTec, Inc.	16,000	18,700
Comprehensive income (loss)	(4,100)	13,200
Eliminations [Member]
Condensed Unaudited Consolidating Statements of Operations and Comprehensive Income (Loss) [Line Items]
Revenue	(7,500)	(23,200)
Costs of revenue, excluding depreciation and amortization	(7,500)	(23,200)
Depreciation and amortization	0	0
General and administrative expenses	0	0
Interest expense (income), net	0	0
Equity in losses (earnings) of unconsolidated affiliates	0	0
Other expense (income), net	0	0
Income before income taxes	0	0
Benefit from (provision for) income taxes	0	0
Net income (loss) before equity in income from subsidiaries	0	0
Equity in income from subsidiaries, net of tax	(36,900)	(43,700)
Net income	(36,900)	(43,700)
Net loss attributable to non-controlling interests	0	0
Net income attributable to MasTec, Inc.	(36,900)	(43,700)
Comprehensive income (loss)	$ (13,600)	$ (38,100)