Supplemental Guarantor Financial Information (Condensed Unaudited Consolidating Statements of Cash Flows) (Details) - USD ($) $ in Thousands	3 Months Ended	6 Months Ended
	Mar. 31, 2017	Jun. 30, 2017	Jun. 30, 2016
Condensed Unaudited Consolidating Statements of Cash Flows [Line Items]
Net cash provided by (used in) operating activities		$ (87,993)	$ 28,488
Cash flows from investing activities:
Cash paid for acquisitions, net of cash acquired		(37,444)	(4,102)
Capital expenditures		(56,853)	(63,893)
Proceeds from sale of property and equipment		7,369	10,163
Payments for other investments		(74,482)	(2,735)
Proceeds from other investments		12,118	695
Net cash used in investing activities		(149,292)	(59,872)
Cash flows from financing activities:
Proceeds from credit facilities		1,153,230	684,287
Repayments of credit facilities		(869,100)	(604,640)
Repayments of other borrowings and capital lease obligations		(41,100)	(33,500)
Payments of acquisition-related contingent consideration		(18,843)	(14,572)
Distributions to non-controlling interests	$ (1,300)	(1,280)	0
Proceeds from stock-based awards, net		5	3,338
Other financing activities, net		(6,240)	1,132
Net financing activities and advances (to) from consolidated affiliates		0	0
Net cash provided by financing activities		216,623	36,046
Effect of currency translation on cash		125	(888)
Net (decrease) increase in cash and cash equivalents		(20,537)	3,774
Cash and cash equivalents - beginning of period	38,767	38,767	4,984
Cash and cash equivalents - end of period		18,230	8,758
Reportable Legal Entities [Member] | MasTec, Inc. [Member]
Condensed Unaudited Consolidating Statements of Cash Flows [Line Items]
Net cash provided by (used in) operating activities		0	0
Cash flows from investing activities:
Cash paid for acquisitions, net of cash acquired		0	0
Capital expenditures		0	0
Proceeds from sale of property and equipment		0	0
Payments for other investments		0	0
Proceeds from other investments		0	0
Net cash used in investing activities		0	0
Cash flows from financing activities:
Proceeds from credit facilities		0	0
Repayments of credit facilities		0	0
Repayments of other borrowings and capital lease obligations		0	0
Payments of acquisition-related contingent consideration		0	0
Distributions to non-controlling interests		0
Proceeds from stock-based awards, net		0	3,300
Other financing activities, net		0	0
Net financing activities and advances (to) from consolidated affiliates		0	(3,300)
Net cash provided by financing activities		0	0
Effect of currency translation on cash		0	0
Net (decrease) increase in cash and cash equivalents		0	0
Cash and cash equivalents - beginning of period	0	0	0
Cash and cash equivalents - end of period		0	0
Reportable Legal Entities [Member] | Guarantor Subsidiaries [Member]
Condensed Unaudited Consolidating Statements of Cash Flows [Line Items]
Net cash provided by (used in) operating activities		(52,900)	(30,200)
Cash flows from investing activities:
Cash paid for acquisitions, net of cash acquired		(37,400)	(4,100)
Capital expenditures		(46,800)	(61,300)
Proceeds from sale of property and equipment		6,800	9,100
Payments for other investments		(1,200)	(1,200)
Proceeds from other investments		0	700
Net cash used in investing activities		(78,600)	(56,800)
Cash flows from financing activities:
Proceeds from credit facilities		1,141,200	625,100
Repayments of credit facilities		(850,200)	(539,100)
Repayments of other borrowings and capital lease obligations		(35,800)	(25,500)
Payments of acquisition-related contingent consideration		(18,800)	(14,600)
Distributions to non-controlling interests		0
Proceeds from stock-based awards, net		0	(300)
Other financing activities, net		(6,200)	1,100
Net financing activities and advances (to) from consolidated affiliates		(115,500)	37,200
Net cash provided by financing activities		114,700	83,900
Effect of currency translation on cash		0	0
Net (decrease) increase in cash and cash equivalents		(16,800)	(3,100)
Cash and cash equivalents - beginning of period	28,300	28,300	4,800
Cash and cash equivalents - end of period		11,400	1,700
Reportable Legal Entities [Member] | Non-Guarantor Subsidiaries [Member]
Condensed Unaudited Consolidating Statements of Cash Flows [Line Items]
Net cash provided by (used in) operating activities		(35,100)	58,700
Cash flows from investing activities:
Cash paid for acquisitions, net of cash acquired		0	0
Capital expenditures		(10,100)	(2,600)
Proceeds from sale of property and equipment		600	1,000
Payments for other investments		(73,300)	(1,500)
Proceeds from other investments		12,100	0
Net cash used in investing activities		(70,700)	(3,100)
Cash flows from financing activities:
Proceeds from credit facilities		12,000	59,200
Repayments of credit facilities		(18,900)	(65,500)
Repayments of other borrowings and capital lease obligations		(5,300)	(8,000)
Payments of acquisition-related contingent consideration		0	0
Distributions to non-controlling interests		(1,300)
Proceeds from stock-based awards, net		0	300
Other financing activities, net		0	0
Net financing activities and advances (to) from consolidated affiliates		115,500	(33,900)
Net cash provided by financing activities		101,900	(47,900)
Effect of currency translation on cash		100	(900)
Net (decrease) increase in cash and cash equivalents		(3,700)	6,800
Cash and cash equivalents - beginning of period	10,500	10,500	200
Cash and cash equivalents - end of period		6,800	7,000
Eliminations [Member]
Condensed Unaudited Consolidating Statements of Cash Flows [Line Items]
Net cash provided by (used in) operating activities		0	0
Cash flows from investing activities:
Cash paid for acquisitions, net of cash acquired		0	0
Capital expenditures		0	0
Proceeds from sale of property and equipment		0	0
Payments for other investments		0	0
Proceeds from other investments		0	0
Net cash used in investing activities		0	0
Cash flows from financing activities:
Proceeds from credit facilities		0	0
Repayments of credit facilities		0	0
Repayments of other borrowings and capital lease obligations		0	0
Payments of acquisition-related contingent consideration		0	0
Distributions to non-controlling interests		0
Proceeds from stock-based awards, net		0	0
Other financing activities, net		0	0
Net financing activities and advances (to) from consolidated affiliates		0	0
Net cash provided by financing activities		0	0
Effect of currency translation on cash		0	0
Net (decrease) increase in cash and cash equivalents		0	0
Cash and cash equivalents - beginning of period	$ 0	0	0
Cash and cash equivalents - end of period		$ 0	$ 0