Supplemental Guarantor Financial Information (Condensed Consolidating Statements of Cash Flows (Unaudited)) (Details) - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018
Condensed Unaudited Consolidating Statements of Cash Flows [Line Items]
Net cash provided by (used in) operating activities	$ 441,394	$ 26,770
Cash flows from investing activities:
Cash paid for acquisitions, net of cash acquired	(94,647)	(6,684)
Capital expenditures	(85,095)	(134,214)
Proceeds from sale of property and equipment	27,102	29,676
Payments for other investments	(5,589)	(36,330)
Proceeds from other investments	14,705	5,415
Net cash used in investing activities	(143,524)	(142,137)
Cash flows from financing activities:
Proceeds from credit facilities	2,185,714	2,422,556
Repayments of credit facilities	(2,371,965)	(1,997,392)
Repayments of other borrowings, net	(333)	(15,830)
Payments of finance lease obligations	(59,045)	(54,560)
Payments of acquisition-related contingent consideration	(29,267)	(15,929)
Proceeds from (distributions to) non-controlling interests	584	(559)
Repurchases of common stock	(5,652)	(198,448)
Proceeds from stock-based awards, net	3,380	3,086
Other financing activities, net	(5,459)	0
Net financing activities and advances from (to) consolidated affiliates	0	0
Net cash (used in) provided by financing activities	(282,043)	142,924
Effect of currency translation on cash	(154)	601
Net increase in cash and cash equivalents	15,673	28,158
Cash and cash equivalents - beginning of period	27,422	40,326
Cash and cash equivalents - end of period	43,095	68,484
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
Payments of acquisition-related contingent consideration	0	0
Proceeds from (distributions to) non-controlling interests	0	0
Repurchases of common stock	(5,700)	(198,400)
Proceeds from stock-based awards, net	3,400	3,100
Other financing activities, net	0
Net financing activities and advances from (to) consolidated affiliates	2,300	195,300
Net cash (used in) 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	416,500	(105,300)
Cash flows from investing activities:
Cash paid for acquisitions, net of cash acquired	(94,600)	(6,700)
Capital expenditures	(81,500)	(130,100)
Proceeds from sale of property and equipment	17,500	20,200
Payments for other investments	(4,300)	(11,800)
Proceeds from other investments	10,800	0
Net cash used in investing activities	(152,100)	(128,400)
Cash flows from financing activities:
Proceeds from credit facilities	2,175,700	2,396,700
Repayments of credit facilities	(2,362,000)	(1,971,200)
Repayments of other borrowings, net	(300)	(15,500)
Payments of finance lease obligations	(57,500)	(49,800)
Payments of acquisition-related contingent consideration	(29,300)	(15,900)
Proceeds from (distributions to) non-controlling interests	0	(600)
Repurchases of common stock	0	0
Proceeds from stock-based awards, net	0	0
Other financing activities, net	(5,500)
Net financing activities and advances from (to) consolidated affiliates	21,400	(71,500)
Net cash (used in) provided by financing activities	(257,500)	272,200
Effect of currency translation on cash	0	0
Net increase in cash and cash equivalents	6,900	38,500
Cash and cash equivalents - beginning of period	11,900	10,000
Cash and cash equivalents - end of period	18,800	48,500
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	24,900	132,100
Cash flows from investing activities:
Cash paid for acquisitions, net of cash acquired	0	0
Capital expenditures	(3,600)	(4,100)
Proceeds from sale of property and equipment	9,600	9,500
Payments for other investments	(1,300)	(24,500)
Proceeds from other investments	3,900	5,400
Net cash used in investing activities	8,600	(13,700)
Cash flows from financing activities:
Proceeds from credit facilities	10,000	25,900
Repayments of credit facilities	(10,000)	(26,200)
Repayments of other borrowings, net	0	(400)
Payments of finance lease obligations	(1,500)	(4,700)
Payments of acquisition-related contingent consideration	0	0
Proceeds from (distributions to) non-controlling interests	600	0
Repurchases of common stock	0	0
Proceeds from stock-based awards, net	0	0
Other financing activities, net	0
Net financing activities and advances from (to) consolidated affiliates	(23,700)	(123,800)
Net cash (used in) provided by financing activities	(24,600)	(129,200)
Effect of currency translation on cash	(200)	600
Net increase in cash and cash equivalents	8,700	(10,200)
Cash and cash equivalents - beginning of period	15,600	30,300
Cash and cash equivalents - end of period	24,300	20,100
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
Payments of acquisition-related contingent consideration	0	0
Proceeds from (distributions to) non-controlling interests	0	0
Repurchases of common stock	0	0
Proceeds from stock-based awards, net	0	0
Other financing activities, net	0
Net financing activities and advances from (to) consolidated affiliates	0	0
Net cash (used in) 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