Supplemental Guarantor Financial Information (Condensed Consolidating Statements of Cash Flows) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Condensed Consolidating Statements of Cash Flows [Line Items]
Net cash provided by (used in) operating activities	$ 156,263	$ 205,593	$ 367,413
Cash flows from investing activities:
Cash paid for acquisitions, net of cash acquired	(115,995)	(4,102)	(148)
Capital expenditures	(123,412)	(117,114)	(84,410)
Proceeds from sale of property and equipment	19,963	11,239	13,932
Payments for other investments	(77,105)	(32,169)	(127,480)
Proceeds from other investments	23,801	1,125	69,406
Net cash used in investing activities	(272,748)	(141,021)	(128,700)
Cash flows from financing activities:
Proceeds from credit facilities	2,699,047	1,681,424	1,702,431
Repayments of credit facilities	(2,457,293)	(1,627,129)	(1,742,077)
Repayments of other borrowings and capital lease obligations, net	(71,100)	(68,700)	(70,900)
Payments of acquisition-related contingent consideration	(18,843)	(19,822)	(47,523)
Payments to non-controlling interests, including acquisition of interests and distributions	(22,728)	0	0
(Payments for) proceeds from stock-based awards, net	(3,085)	4,200	1,566
Repurchase of common stock	(1,552)	0	(100,000)
Other financing activities, net	(6,301)	515	(2,379)
Net financing activities and advances from (to) consolidated affiliates	0	0	0
Net cash provided by (used in) financing activities	118,155	(29,486)	(258,920)
Effect of currency translation on cash	(111)	(1,303)	1,132
Net increase (decrease) in cash and cash equivalents	1,559	33,783	(19,075)
Cash and cash equivalents - beginning of period	38,767	4,984	24,059
Cash and cash equivalents - end of period	40,326	38,767	4,984
Reportable Legal Entities [Member] | MasTec, Inc. [Member]
Condensed Consolidating Statements of Cash Flows [Line Items]
Net cash provided by (used in) operating activities	0	0	900
Cash flows from investing activities:
Cash paid for acquisitions, net of cash acquired	0	0	0
Capital expenditures	0	0	0
Proceeds from sale of property and equipment	0	0	0
Payments for other investments	0	0	(1,900)
Proceeds from other investments	0	0	0
Net cash used in investing activities	0	0	(1,900)
Cash flows from financing activities:
Proceeds from credit facilities	0	0	0
Repayments of credit facilities	0	0	0
Repayments of other borrowings and capital lease obligations, net	0	0	0
Payments of acquisition-related contingent consideration	0	0	0
Payments to non-controlling interests, including acquisition of interests and distributions	0
(Payments for) proceeds from stock-based awards, net	(3,100)	4,200	2,700
Repurchase of common stock	(1,600)		(100,000)
Other financing activities, net	0	100	0
Net financing activities and advances from (to) consolidated affiliates	4,700	(4,300)	98,300
Net cash provided by (used in) financing activities	0	0	1,000
Effect of currency translation on cash	0	0	0
Net increase (decrease) in cash and cash equivalents	0	0	0
Cash and cash equivalents - beginning of period	0	0	0
Cash and cash equivalents - end of period	0	0	0
Reportable Legal Entities [Member] | Guarantor Subsidiaries [Member]
Condensed Consolidating Statements of Cash Flows [Line Items]
Net cash provided by (used in) operating activities	155,100	130,500	358,500
Cash flows from investing activities:
Cash paid for acquisitions, net of cash acquired	(116,000)	(4,100)	(100)
Capital expenditures	(120,100)	(112,600)	(71,900)
Proceeds from sale of property and equipment	18,200	7,600	10,500
Payments for other investments	(3,800)	(3,900)	0
Proceeds from other investments	1,200	0	0
Net cash used in investing activities	(220,500)	(113,000)	(61,500)
Cash flows from financing activities:
Proceeds from credit facilities	2,674,400	1,553,400	1,097,300
Repayments of credit facilities	(2,428,900)	(1,496,600)	(1,154,300)
Repayments of other borrowings and capital lease obligations, net	(61,500)	(50,400)	(54,300)
Payments of acquisition-related contingent consideration	(18,800)	(16,600)	(37,300)
Payments to non-controlling interests, including acquisition of interests and distributions	(22,700)
(Payments for) proceeds from stock-based awards, net	0	0	(1,100)
Repurchase of common stock	0		0
Other financing activities, net	(6,300)	400	(2,400)
Net financing activities and advances from (to) consolidated affiliates	(89,600)	16,400	(158,600)
Net cash provided by (used in) financing activities	46,600	6,600	(310,700)
Effect of currency translation on cash	0	0	0
Net increase (decrease) in cash and cash equivalents	(18,800)	24,100	(13,700)
Cash and cash equivalents - beginning of period	28,900	4,800	18,500
Cash and cash equivalents - end of period	10,100	28,900	4,800
Reportable Legal Entities [Member] | Non-Guarantor Subsidiaries [Member]
Condensed Consolidating Statements of Cash Flows [Line Items]
Net cash provided by (used in) operating activities	1,200	75,100	8,000
Cash flows from investing activities:
Cash paid for acquisitions, net of cash acquired	0	0	0
Capital expenditures	(3,300)	(4,500)	(12,500)
Proceeds from sale of property and equipment	1,800	3,600	3,400
Payments for other investments	(73,300)	(28,200)	(125,600)
Proceeds from other investments	22,600	1,100	69,400
Net cash used in investing activities	(52,200)	(28,000)	(65,300)
Cash flows from financing activities:
Proceeds from credit facilities	24,600	128,000	605,100
Repayments of credit facilities	(28,400)	(130,500)	(587,800)
Repayments of other borrowings and capital lease obligations, net	(9,600)	(18,300)	(16,600)
Payments of acquisition-related contingent consideration	0	(3,200)	(10,200)
Payments to non-controlling interests, including acquisition of interests and distributions	0
(Payments for) proceeds from stock-based awards, net	0	0	0
Repurchase of common stock	0		0
Other financing activities, net	0	0	0
Net financing activities and advances from (to) consolidated affiliates	84,900	(12,100)	60,300
Net cash provided by (used in) financing activities	71,500	(36,100)	50,800
Effect of currency translation on cash	(100)	(1,300)	1,100
Net increase (decrease) in cash and cash equivalents	20,400	9,700	(5,400)
Cash and cash equivalents - beginning of period	9,900	200	5,600
Cash and cash equivalents - end of period	30,300	9,900	200
Eliminations [Member]
Condensed Consolidating Statements of Cash Flows [Line Items]
Net cash provided by (used in) operating activities	0	0	0
Cash flows from investing activities:
Cash paid for acquisitions, net of cash acquired	0	0	0
Capital expenditures	0	0	0
Proceeds from sale of property and equipment	0	0	0
Payments for other investments	0	0	0
Proceeds from other investments	0	0	0
Net cash used in investing activities	0	0	0
Cash flows from financing activities:
Proceeds from credit facilities	0	0	0
Repayments of credit facilities	0	0	0
Repayments of other borrowings and capital lease obligations, net	0	0	0
Payments of acquisition-related contingent consideration	0	0	0
Payments to non-controlling interests, including acquisition of interests and distributions	0
(Payments for) proceeds from stock-based awards, net	0	0	0
Repurchase of common stock	0		0
Other financing activities, net	0	0	0
Net financing activities and advances from (to) consolidated affiliates	0	0	0
Net cash provided by (used in) financing activities	0	0	0
Effect of currency translation on cash	0	0	0
Net increase (decrease) in cash and cash equivalents	0	0	0
Cash and cash equivalents - beginning of period	0	0	0
Cash and cash equivalents - end of period	$ 0	$ 0	$ 0