Supplemental Guarantor Financial Information (Condensed Unaudited Consolidating Statements of Operations and Comprehensive Income (Loss)) (Details) - USD ($) $ in Thousands		3 Months Ended		6 Months Ended
		Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018
Condensed Unaudited Consolidating Statements of Operations and Comprehensive Income (Loss) [Line Items]
Revenue		$ 1,939,006	$ 1,617,804	$ 3,457,346	$ 3,014,638
Costs of revenue, excluding depreciation and amortization		1,633,400	1,366,584	2,945,448	2,603,883
Depreciation and amortization		59,944	51,676	118,975	101,615
General and administrative expenses		70,819	67,602	143,436	131,224
Interest expense (income), net		16,623	20,795	38,881	37,854
Equity in earnings of unconsolidated affiliates		(6,551)	(5,824)	(12,811)	(11,409)
Other expense (income), net		4,812	788	8,317	(2,301)
Income before income taxes		159,959	116,183	215,100	153,772
(Provision for) benefit from income taxes		(39,736)	(35,782)	(51,770)	(46,908)
Net income (loss) before equity in income from subsidiaries		120,200	80,400	163,300	106,900
Equity in income (losses) from subsidiaries, net of tax		0	0	0	0
Net income		120,223	80,401	163,330	106,864
Net income (loss) attributable to non-controlling interests		513	(91)	507	(188)
Net income attributable to MasTec, Inc.	[1]	119,710	80,492	162,823	107,052
Comprehensive income (loss)		111,604	81,686	149,149	115,342
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	800	1,600	1,500
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)	(800)	(1,600)	(1,500)
(Provision for) benefit from income taxes		300	200	600	400
Net income (loss) before equity in income from subsidiaries		(500)	(600)	(1,000)	(1,100)
Equity in income (losses) from subsidiaries, net of tax		120,200	81,100	163,800	108,200
Net income		119,700	80,500	162,800	107,100
Net income (loss) attributable to non-controlling interests		0	0	0	0
Net income attributable to MasTec, Inc.		119,700	80,500	162,800	107,100
Comprehensive income (loss)		111,100	81,800	148,600	115,500
Reportable Legal Entities [Member] | Guarantor Subsidiaries [Member]
Condensed Unaudited Consolidating Statements of Operations and Comprehensive Income (Loss) [Line Items]
Revenue		1,845,900	1,556,900	3,247,100	2,822,500
Costs of revenue, excluding depreciation and amortization		1,546,100	1,309,100	2,745,600	2,445,300
Depreciation and amortization		55,400	46,200	109,900	89,500
General and administrative expenses		66,000	63,100	133,300	122,400
Interest expense (income), net		32,500	37,100	70,200	70,000
Equity in earnings of unconsolidated affiliates		(0)	0	100	0
Other expense (income), net		40,200	1,200	45,200	(1,400)
Income before income taxes		105,700	100,200	142,800	96,700
(Provision for) benefit from income taxes		(39,000)	(25,900)	(51,000)	(24,900)
Net income (loss) before equity in income from subsidiaries		66,700	74,300	91,800	71,800
Equity in income (losses) from subsidiaries, net of tax		0	0	0	0
Net income		66,700	74,300	91,800	71,800
Net income (loss) attributable to non-controlling interests		0	0	0	0
Net income attributable to MasTec, Inc.		66,700	74,300	91,800	71,800
Comprehensive income (loss)		66,700	74,300	91,800	71,800
Reportable Legal Entities [Member] | Non-Guarantor Subsidiaries [Member]
Condensed Unaudited Consolidating Statements of Operations and Comprehensive Income (Loss) [Line Items]
Revenue		122,300	84,000	262,600	269,600
Costs of revenue, excluding depreciation and amortization		116,500	80,600	252,200	236,100
Depreciation and amortization		4,500	5,500	9,100	12,100
General and administrative expenses		4,100	3,700	8,500	7,300
Interest expense (income), net		(15,900)	(16,300)	(31,300)	(32,100)
Equity in earnings of unconsolidated affiliates		(6,600)	(5,800)	(12,900)	(11,400)
Other expense (income), net		(35,400)	(400)	(36,900)	(900)
Income before income taxes		55,100	16,700	73,900	58,500
(Provision for) benefit from income taxes		(1,000)	(10,100)	(1,400)	(22,300)
Net income (loss) before equity in income from subsidiaries		54,100	6,600	72,500	36,200
Equity in income (losses) from subsidiaries, net of tax		0	0	0	0
Net income		54,100	6,600	72,500	36,200
Net income (loss) attributable to non-controlling interests		500	(100)	500	(200)
Net income attributable to MasTec, Inc.		53,600	6,700	72,000	36,400
Comprehensive income (loss)		45,500	8,000	58,400	44,700
Eliminations [Member]
Condensed Unaudited Consolidating Statements of Operations and Comprehensive Income (Loss) [Line Items]
Revenue		(29,200)	(23,100)	(52,400)	(77,500)
Costs of revenue, excluding depreciation and amortization		(29,200)	(23,100)	(52,400)	(77,500)
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		(120,200)	(81,100)	(163,800)	(108,200)
Net income		(120,200)	(81,100)	(163,800)	(108,200)
Net income (loss) attributable to non-controlling interests		0	0	0	0
Net income attributable to MasTec, Inc.		(120,200)	(81,100)	(163,800)	(108,200)
Comprehensive income (loss)		$ (111,600)	$ (82,400)	$ (149,700)	$ (116,700)

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