Supplemental Guarantor Financial Information (Condensed Consolidating Statements of Cash Flows) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Condensed Consolidating Statements of Cash Flows [Line Items]
Net cash provided by (used in) operating activities	$ 550,278	$ 529,956	$ 144,096
Cash flows from investing activities:
Cash paid for acquisitions, net of cash acquired	(179,481)	(6,684)	(115,995)
Capital expenditures	(126,473)	(180,420)	(123,412)
Proceeds from sale of property and equipment	35,015	39,359	19,963
Payments for other investments	(5,589)	(39,469)	(77,105)
Proceeds from other investments	14,705	5,415	23,801
Net cash used in investing activities	(261,823)	(181,799)	(272,748)
Cash flows from financing activities:
Proceeds from credit facilities	3,025,927	3,418,232	2,699,047
Repayments of credit facilities	(3,126,595)	(3,359,521)	(2,457,293)
Repayments of other borrowings, net	(12,438)	(17,427)	(3,350)
Payments of finance lease obligations	(88,341)	(72,167)	(67,740)
Payments of acquisition-related contingent consideration	(34,267)	(15,929)	(6,676)
Distributions to (proceeds from) non-controlling interests	(583)	559	22,728
Proceeds from stock-based awards	4,655	4,047	3,104
Payments for stock-based awards	(45)	(3,821)	(6,189)
Repurchases of common stock	(5,652)	(313,949)	(1,552)
Other financing activities, net	(8,458)	0	(6,301)
Net financing activities and advances from (to) consolidated affiliates	0	0	0
Net cash (used in) provided by financing activities	(244,631)	(361,094)	130,322
Effect of currency translation on cash	181	33	(111)
Net increase (decrease) in cash and cash equivalents	44,005	(12,904)	1,559
Cash and cash equivalents - beginning of period	27,422	40,326	38,767
Cash and cash equivalents - end of period	71,427	27,422	40,326
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	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, net	0	0	0
Payments of finance lease obligations	0	0	0
Payments of acquisition-related contingent consideration	0	0	0
Distributions to (proceeds from) non-controlling interests	0	0	0
Proceeds from stock-based awards	4,700	4,000	3,100
Payments for stock-based awards		(3,800)	(6,200)
Repurchases of common stock	(5,700)	(313,900)	(1,600)
Other financing activities, net	0	0	0
Net financing activities and advances from (to) consolidated affiliates	1,000	313,700	4,700
Net cash (used in) provided by 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
Reportable Legal Entities [Member] | Guarantor Subsidiaries [Member]
Condensed Consolidating Statements of Cash Flows [Line Items]
Net cash provided by (used in) operating activities	467,200	341,600	142,900
Cash flows from investing activities:
Cash paid for acquisitions, net of cash acquired	(179,500)	(6,700)	(116,000)
Capital expenditures	(120,800)	(174,300)	(120,100)
Proceeds from sale of property and equipment	24,800	26,200	18,200
Payments for other investments	(4,300)	(11,800)	(3,800)
Proceeds from other investments	10,800	0	1,200
Net cash used in investing activities	(269,000)	(166,600)	(220,500)
Cash flows from financing activities:
Proceeds from credit facilities	3,015,300	3,383,900	2,674,400
Repayments of credit facilities	(3,116,000)	(3,314,800)	(2,428,900)
Repayments of other borrowings, net	(9,700)	(17,100)	(2,300)
Payments of finance lease obligations	(86,300)	(66,600)	(59,200)
Payments of acquisition-related contingent consideration	(34,300)	(15,900)	(6,600)
Distributions to (proceeds from) non-controlling interests	0	600	22,700
Proceeds from stock-based awards	0	0	0
Payments for stock-based awards		0	0
Repurchases of common stock	0	0	0
Other financing activities, net	(5,500)	0	(6,300)
Net financing activities and advances from (to) consolidated affiliates	62,800	(142,100)	(89,600)
Net cash (used in) provided by financing activities	(173,700)	(173,200)	58,800
Effect of currency translation on cash	0	0	0
Net increase (decrease) in cash and cash equivalents	24,500	1,800	(18,800)
Cash and cash equivalents - beginning of period	11,900	10,100	28,900
Cash and cash equivalents - end of period	36,400	11,900	10,100
Reportable Legal Entities [Member] | Non-Guarantor Subsidiaries [Member]
Condensed Consolidating Statements of Cash Flows [Line Items]
Net cash provided by (used in) operating activities	83,100	188,400	1,200
Cash flows from investing activities:
Cash paid for acquisitions, net of cash acquired	0	0	0
Capital expenditures	(5,700)	(6,100)	(3,300)
Proceeds from sale of property and equipment	10,200	13,100	1,800
Payments for other investments	(1,300)	(27,600)	(73,300)
Proceeds from other investments	3,900	5,400	22,600
Net cash used in investing activities	7,100	(15,200)	(52,200)
Cash flows from financing activities:
Proceeds from credit facilities	10,600	34,300	24,600
Repayments of credit facilities	(10,600)	(44,700)	(28,400)
Repayments of other borrowings, net	(2,700)	(300)	(1,100)
Payments of finance lease obligations	(2,000)	(5,600)	(8,500)
Payments of acquisition-related contingent consideration	0	0	0
Distributions to (proceeds from) non-controlling interests	(600)	0	0
Proceeds from stock-based awards	0	0	0
Payments for stock-based awards		0	0
Repurchases of common stock	0	0	0
Other financing activities, net	(3,000)	0	0
Net financing activities and advances from (to) consolidated affiliates	(63,800)	(171,600)	84,900
Net cash (used in) provided by financing activities	(70,900)	(187,900)	71,500
Effect of currency translation on cash	200	0	(100)
Net increase (decrease) in cash and cash equivalents	19,500	(14,700)	20,400
Cash and cash equivalents - beginning of period	15,600	30,300	9,900
Cash and cash equivalents - end of period	35,100	15,600	30,300
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, net	0	0	0
Payments of finance lease obligations	0	0	0
Payments of acquisition-related contingent consideration	0	0	0
Distributions to (proceeds from) non-controlling interests	0	0	0
Proceeds from stock-based awards	0	0	0
Payments for stock-based awards		0	0
Repurchases of common stock	0	0	0
Other financing activities, net	0	0	0
Net financing activities and advances from (to) consolidated affiliates	0	0	0
Net cash (used in) provided by 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