Supplemental Guarantor Financial Information (Condensed Unaudited Consolidating Statements of Cash Flows) (Details) - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017
Condensed Unaudited Consolidating Statements of Cash Flows [Line Items]
Net cash provided by (used in) operating activities	$ 26,770	$ 166,458
Cash flows from investing activities:
Cash paid for acquisitions, net of cash acquired	(6,684)	(115,995)
Capital expenditures	(134,214)	(83,330)
Proceeds from sale of property and equipment	29,676	13,585
Payments for other investments	(36,330)	(77,105)
Proceeds from other investments	5,415	13,416
Net cash used in investing activities	(142,137)	(249,429)
Cash flows from financing activities:
Proceeds from credit facilities	2,422,556	2,002,430
Repayments of credit facilities	(1,997,392)	(1,840,409)
Repayments of other borrowings and capital lease obligations	(70,400)	(60,800)
Payments of acquisition-related contingent consideration	(15,929)	(6,676)
Repurchase of common stock	(198,448)	0
Distributions to non-controlling interests	(559)	(1,280)
Proceeds from stock-based awards, net	3,086	853
Other financing activities	0	(6,301)
Net financing activities and advances from (to) consolidated affiliates	0	0
Net cash provided by financing activities	142,924	87,789
Effect of currency translation on cash	601	237
Net increase in cash and cash equivalents	28,158	5,055
Cash and cash equivalents - beginning of period	40,326	38,767
Cash and cash equivalents - end of period	68,484	43,822
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
Repurchase of common stock	(198,400)
Distributions to non-controlling interests	0	0
Proceeds from stock-based awards, net	3,100	900
Other financing activities		0
Net financing activities and advances from (to) consolidated affiliates	195,300	(900)
Net cash provided by financing activities	0	0
Effect of currency translation on cash	0	0
Net increase 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	(105,300)	229,000
Cash flows from investing activities:
Cash paid for acquisitions, net of cash acquired	(6,700)	(116,000)
Capital expenditures	(130,100)	(80,600)
Proceeds from sale of property and equipment	20,200	12,500
Payments for other investments	(11,800)	(3,800)
Proceeds from other investments	0	1,200
Net cash used in investing activities	(128,400)	(186,700)
Cash flows from financing activities:
Proceeds from credit facilities	2,396,700	1,988,100
Repayments of credit facilities	(1,971,200)	(1,817,400)
Repayments of other borrowings and capital lease obligations	(65,300)	(53,600)
Payments of acquisition-related contingent consideration	(15,900)	(6,700)
Repurchase of common stock	0
Distributions to non-controlling interests	(600)	(1,300)
Proceeds from stock-based awards, net	0	0
Other financing activities		(6,300)
Net financing activities and advances from (to) consolidated affiliates	(71,500)	(136,800)
Net cash provided by financing activities	272,200	(34,000)
Effect of currency translation on cash	0	0
Net increase in cash and cash equivalents	38,500	8,300
Cash and cash equivalents - beginning of period	10,000	28,900
Cash and cash equivalents - end of period	48,500	37,200
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	132,100	(62,500)
Cash flows from investing activities:
Cash paid for acquisitions, net of cash acquired	0	0
Capital expenditures	(4,100)	(2,700)
Proceeds from sale of property and equipment	9,500	1,100
Payments for other investments	(24,500)	(73,300)
Proceeds from other investments	5,400	12,200
Net cash used in investing activities	(13,700)	(62,700)
Cash flows from financing activities:
Proceeds from credit facilities	25,900	14,300
Repayments of credit facilities	(26,200)	(23,000)
Repayments of other borrowings and capital lease obligations	(5,100)	(7,300)
Payments of acquisition-related contingent consideration	0	0
Repurchase of common stock	0
Distributions to non-controlling interests	0	0
Proceeds from stock-based awards, net	0	0
Other financing activities		0
Net financing activities and advances from (to) consolidated affiliates	(123,800)	137,700
Net cash provided by financing activities	(129,200)	121,700
Effect of currency translation on cash	600	200
Net increase in cash and cash equivalents	(10,200)	(3,300)
Cash and cash equivalents - beginning of period	30,300	9,900
Cash and cash equivalents - end of period	20,100	6,600
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
Repurchase of common stock	0
Distributions to non-controlling interests	0	0
Proceeds from stock-based awards, net	0	0
Other financing activities		0
Net financing activities and advances from (to) consolidated affiliates	0	0
Net cash provided by financing activities	0	0
Effect of currency translation on cash	0	0
Net increase 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