Supplemental Guarantor Financial Information (Condensed Unaudited Consolidating Statements of Cash Flows) (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Condensed Unaudited Consolidating Statements of Cash Flows [Line Items]
Net cash provided by (used in) operating activities	$ (46,807)	$ 83,501
Cash flows from investing activities:
Cash paid for acquisitions, net of cash acquired	(93,684)	(4,329)
Capital expenditures	(34,396)	(22,545)
Proceeds from sale of property and equipment	8,654	5,382
Payments for other investments	(2,190)	(14,779)
Proceeds from other investments	10,413	5,415
Net cash used in investing activities	(111,203)	(30,856)
Cash flows from financing activities:
Proceeds from credit facilities	866,397	816,888
Repayments of credit facilities	(670,794)	(747,099)
Repayments of other borrowings, net	(6)	(14,612)
Payments of finance lease obligations	(17,239)	(18,112)
Repurchases of common stock	(5,652)	(90,880)
Distributions to non-controlling interests	0	(559)
Proceeds from stock-based awards, net	1,067	916
Net financing activities and advances from (to) consolidated affiliates	0	0
Net cash provided by (used in) financing activities	173,773	(53,458)
Effect of currency translation on cash	9	722
Net increase (decrease) in cash and cash equivalents	15,772	(91)
Cash and cash equivalents - beginning of period	27,422	40,326
Cash and cash equivalents - end of period	43,194	40,235
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, net	0	0
Payments of finance lease obligations	0	0
Repurchases of common stock	(5,700)	(90,900)
Distributions to non-controlling interests		0
Proceeds from stock-based awards, net	1,100	900
Net financing activities and advances from (to) consolidated affiliates	4,600	90,000
Net cash provided by (used in) financing activities	0	0
Effect of currency translation on cash	0	0
Net increase (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	(43,500)	114,000
Cash flows from investing activities:
Cash paid for acquisitions, net of cash acquired	(93,700)	(4,300)
Capital expenditures	(32,900)	(22,400)
Proceeds from sale of property and equipment	4,800	4,800
Payments for other investments	(1,400)	0
Proceeds from other investments	10,400	0
Net cash used in investing activities	(112,800)	(21,900)
Cash flows from financing activities:
Proceeds from credit facilities	862,700	810,600
Repayments of credit facilities	(667,200)	(736,600)
Repayments of other borrowings, net	0	(14,400)
Payments of finance lease obligations	(16,700)	(16,200)
Repurchases of common stock	0	0
Distributions to non-controlling interests		(600)
Proceeds from stock-based awards, net	0	0
Net financing activities and advances from (to) consolidated affiliates	(27,300)	(132,300)
Net cash provided by (used in) financing activities	151,500	(89,500)
Effect of currency translation on cash	0	0
Net increase (decrease) in cash and cash equivalents	(4,800)	2,600
Cash and cash equivalents - beginning of period	11,900	10,000
Cash and cash equivalents - end of period	7,100	12,600
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	(3,300)	(30,500)
Cash flows from investing activities:
Cash paid for acquisitions, net of cash acquired	0	0
Capital expenditures	(1,500)	(100)
Proceeds from sale of property and equipment	3,900	600
Payments for other investments	(800)	(14,800)
Proceeds from other investments	0	5,400
Net cash used in investing activities	1,600	(8,900)
Cash flows from financing activities:
Proceeds from credit facilities	3,700	6,300
Repayments of credit facilities	(3,600)	(10,500)
Repayments of other borrowings, net	0	(200)
Payments of finance lease obligations	(500)	(1,900)
Repurchases of common stock	0	0
Distributions to non-controlling interests		0
Proceeds from stock-based awards, net	0	0
Net financing activities and advances from (to) consolidated affiliates	22,700	42,300
Net cash provided by (used in) financing activities	22,300	36,000
Effect of currency translation on cash	0	700
Net increase (decrease) in cash and cash equivalents	20,600	(2,700)
Cash and cash equivalents - beginning of period	15,600	30,300
Cash and cash equivalents - end of period	36,200	27,600
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, net	0	0
Payments of finance lease obligations	0	0
Repurchases of common stock	0	0
Distributions to non-controlling interests		0
Proceeds from stock-based awards, net	0	0
Net financing activities and advances from (to) consolidated affiliates	0	0
Net cash provided by (used in) financing activities	0	0
Effect of currency translation on cash	0	0
Net increase (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