Supplemental Guarantor Financial Information (Condensed Unaudited Consolidating Statements of Cash Flows) (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Condensed Unaudited Consolidating Statements of Cash Flows [Line Items]
Net cash provided by (used in) operating activities	$ 83,501	$ 154,173
Cash flows from investing activities:
Cash paid for acquisitions, net of cash acquired	(4,329)	0
Capital expenditures	(22,545)	(28,901)
Proceeds from sale of property and equipment	5,382	511
Payments for other investments	(14,779)	(53,347)
Proceeds from other investments	5,415	12,118
Net cash used in investing activities	(30,856)	(69,619)
Cash flows from financing activities:
Proceeds from credit facilities	816,888	361,743
Repayments of credit facilities	(747,099)	(447,112)
Repayments of other borrowings and capital lease obligations	(32,700)	(14,400)
Repurchase of common stock	(90,880)	0
Distributions to non-controlling interests	(559)	(1,280)
Proceeds from stock-based awards, net	916
Payments for stock-based awards, net		(761)
Other financing activities	0	(5,973)
Net financing activities and advances from (to) consolidated affiliates	0	0
Net cash used in financing activities	(53,458)	(107,794)
Effect of currency translation on cash	722	160
Net decrease in cash and cash equivalents	(91)	(23,080)
Cash and cash equivalents - beginning of period	40,326	38,767
Cash and cash equivalents - end of period	40,235	15,687
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
Repurchase of common stock	(90,900)
Distributions to non-controlling interests	0	0
Proceeds from stock-based awards, net	900
Payments for stock-based awards, net		(800)
Other financing activities		0
Net financing activities and advances from (to) consolidated affiliates	90,000	800
Net cash used in financing activities	0	0
Effect of currency translation on cash	0	0
Net decrease in cash and cash equivalents	0	0
Cash and cash equivalents - beginning of period	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	114,000	179,500
Cash flows from investing activities:
Cash paid for acquisitions, net of cash acquired	(4,300)	0
Capital expenditures	(22,400)	(27,800)
Proceeds from sale of property and equipment	4,800	400
Payments for other investments	0	0
Proceeds from other investments	0	0
Net cash used in investing activities	(21,900)	(27,400)
Cash flows from financing activities:
Proceeds from credit facilities	810,600	357,200
Repayments of credit facilities	(736,600)	(439,000)
Repayments of other borrowings and capital lease obligations	(30,600)	(12,000)
Repurchase of common stock	0
Distributions to non-controlling interests	(600)	(1,300)
Proceeds from stock-based awards, net	0
Payments for stock-based awards, net		0
Other financing activities		(6,000)
Net financing activities and advances from (to) consolidated affiliates	(132,300)	(78,800)
Net cash used in financing activities	(89,500)	(179,900)
Effect of currency translation on cash	0	0
Net decrease in cash and cash equivalents	2,600	(27,800)
Cash and cash equivalents - beginning of period	10,000	28,900
Cash and cash equivalents - end of period	12,600	1,100
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	(30,500)	(25,300)
Cash flows from investing activities:
Cash paid for acquisitions, net of cash acquired	0	0
Capital expenditures	(100)	(1,100)
Proceeds from sale of property and equipment	600	100
Payments for other investments	(14,800)	(53,300)
Proceeds from other investments	5,400	12,100
Net cash used in investing activities	(8,900)	(42,200)
Cash flows from financing activities:
Proceeds from credit facilities	6,300	4,500
Repayments of credit facilities	(10,500)	(8,100)
Repayments of other borrowings and capital lease obligations	(2,100)	(2,300)
Repurchase of common stock	0
Distributions to non-controlling interests	0	0
Proceeds from stock-based awards, net	0
Payments for stock-based awards, net		0
Other financing activities		0
Net financing activities and advances from (to) consolidated affiliates	42,300	78,000
Net cash used in financing activities	36,000	72,100
Effect of currency translation on cash	700	200
Net decrease in cash and cash equivalents	(2,700)	4,800
Cash and cash equivalents - beginning of period	30,300	9,900
Cash and cash equivalents - end of period	27,600	14,700
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
Repurchase of common stock	0
Distributions to non-controlling interests	0	0
Proceeds from stock-based awards, net	0
Payments for stock-based awards, net		0
Other financing activities		0
Net financing activities and advances from (to) consolidated affiliates	0	0
Net cash used in financing activities	0	0
Effect of currency translation on cash	0	0
Net decrease in cash and cash equivalents	0	0
Cash and cash equivalents - beginning of period	0	0
Cash and cash equivalents - end of period	$ 0	$ 0