Supplemental Guarantor Financial Information (Condensed Consolidating Statements of Cash Flows) (Details) - USD ($) $ in Thousands	3 Months Ended	6 Months Ended	9 Months Ended	12 Months Ended
	Mar. 31, 2014	Jun. 30, 2014	Sep. 30, 2014	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Condensed Consolidating Statements of Cash Flows [Line Items]
Net cash (used in) provided by operating activities	$ (20,394)	$ 55,319	$ 81,019	$ 323,011	$ 200,402	$ 172,508
Cash flows (used in) provided by investing activities:
Cash paid for acquisitions, net of cash acquired	(23,831)	(162,901)	(162,901)	(345,543)	(148,567)	(119,459)
Proceeds from disposal of business, net of cash divested			0	0	(2,997)	97,728
Capital expenditures	(35,554)	(67,566)	(90,962)	(109,254)	(126,288)	(79,686)
Proceeds from sale of property and equipment	3,373	8,752	12,204	16,655	15,858	7,385
Payments for investments, net				(1,100)	(1,200)	(200)
Net cash used in investing activities	(57,110)	(221,142)	(242,705)	(439,262)	(263,211)	(94,316)
Cash flows provided by (used in) financing activities:
Proceeds from credit facilities	233,872	815,840	1,319,623	2,385,971	1,149,040	959,183
Repayments of credit facilities	(157,349)	(463,713)	(955,151)	(1,939,612)	(1,249,601)	(885,183)
(Repayments of) proceeds from senior notes, net				(202,300)	250,000
Repayments of other borrowings and capital lease obligations				(67,300)	(70,700)	(42,500)
Repurchase of common stock				0	0	(75,000)
Proceeds from stock-based awards, net of tax withholdings	(1,451)	(578)	318	1,113	8,355	5,013
Excess tax benefit from stock-based compensation	3,246	3,386	3,494	3,728	4,315	759
Payments of acquisition-related contingent consideration		(58,902)	(60,341)	(60,341)	(18,683)	(33,936)
Payments of financing costs, including call premiums on extinguishment of debt	(218)	(1,298)	(1,455)	(2,572)	(13,688)	(117)
Net financing activities and advances (to) from consolidated affiliates				0	0	0
Net cash provided by (used in) financing activities	64,314	159,167	146,978	118,675	58,993	(71,796)
Effect of currency translation on cash	(476)	(347)	(1,152)	(1,292)	(24)	91
Net increase (decrease) in cash and cash equivalents	(13,666)	(7,003)	(15,860)	1,132	(3,840)	6,487
Cash and cash equivalents - beginning of period	22,927	22,927	22,927	22,927	26,767	20,280
Cash and cash equivalents - end of period	9,261	15,924	7,067	24,059	22,927	26,767
Reportable Legal Entities [Member] | MasTec, Inc. [Member]
Condensed Consolidating Statements of Cash Flows [Line Items]
Net cash (used in) provided by operating activities				(500)	(1,700)	(1,300)
Cash flows (used in) provided by investing activities:
Cash paid for acquisitions, net of cash acquired				0	0	0
Proceeds from disposal of business, net of cash divested					0	0
Capital expenditures				0	0	0
Proceeds from sale of property and equipment				0	0	0
Payments for investments, net				(1,000)	(1,200)	(200)
Net cash used in investing activities				(1,000)	(1,200)	(200)
Cash flows provided by (used in) financing activities:
Proceeds from credit facilities				0	0	0
Repayments of credit facilities				0	0	0
(Repayments of) proceeds from senior notes, net				0	0
Repayments of other borrowings and capital lease obligations				0	0	0
Repurchase of common stock						(75,000)
Proceeds from stock-based awards, net of tax withholdings				3,800	9,900	5,000
Excess tax benefit from stock-based compensation				0	0	0
Payments of acquisition-related contingent consideration				0	0	0
Payments of financing costs, including call premiums on extinguishment of debt				0	0	0
Net financing activities and advances (to) from consolidated affiliates				(2,300)	(7,000)	71,500
Net cash provided by (used in) financing activities				1,500	2,900	1,500
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	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 (used in) provided by operating activities				253,900	174,100	159,200
Cash flows (used in) provided by investing activities:
Cash paid for acquisitions, net of cash acquired				(222,700)	(45,000)	(54,000)
Proceeds from disposal of business, net of cash divested					(3,000)	0
Capital expenditures				(84,800)	(114,400)	(78,100)
Proceeds from sale of property and equipment				14,300	14,700	7,300
Payments for investments, net				(100)	0	0
Net cash used in investing activities				(293,300)	(147,700)	(124,800)
Cash flows provided by (used in) financing activities:
Proceeds from credit facilities				1,894,400	961,600	959,200
Repayments of credit facilities				(1,410,000)	(1,042,200)	(885,200)
(Repayments of) proceeds from senior notes, net				(202,300)	250,000
Repayments of other borrowings and capital lease obligations				(40,900)	(69,100)	(42,500)
Repurchase of common stock						0
Proceeds from stock-based awards, net of tax withholdings				(2,700)	(1,500)	0
Excess tax benefit from stock-based compensation				3,700	4,300	800
Payments of acquisition-related contingent consideration				(60,300)	(16,700)	(27,800)
Payments of financing costs, including call premiums on extinguishment of debt				(2,600)	(13,700)	(100)
Net financing activities and advances (to) from consolidated affiliates				(126,800)	(106,400)	(31,700)
Net cash provided by (used in) financing activities				52,500	(33,700)	(27,300)
Effect of currency translation on cash				0	0	0
Net increase (decrease) in cash and cash equivalents				13,100	(7,300)	7,100
Cash and cash equivalents - beginning of period	5,400	5,400	5,400	5,400	12,700	5,600
Cash and cash equivalents - end of period				18,500	5,400	12,700
Reportable Legal Entities [Member] | Non-Guarantor Subsidiaries [Member]
Condensed Consolidating Statements of Cash Flows [Line Items]
Net cash (used in) provided by operating activities				69,600	28,000	14,600
Cash flows (used in) provided by investing activities:
Cash paid for acquisitions, net of cash acquired				(122,900)	(103,600)	(65,500)
Proceeds from disposal of business, net of cash divested					0	97,700
Capital expenditures				(24,500)	(11,900)	(1,600)
Proceeds from sale of property and equipment				2,400	1,200	100
Payments for investments, net				0	0	0
Net cash used in investing activities				(145,000)	(114,300)	30,700
Cash flows provided by (used in) financing activities:
Proceeds from credit facilities				491,600	187,400	0
Repayments of credit facilities				(529,600)	(207,400)	0
(Repayments of) proceeds from senior notes, net				0	0
Repayments of other borrowings and capital lease obligations				(26,400)	(1,600)	0
Repurchase of common stock						0
Proceeds from stock-based awards, net of tax withholdings				0	0	0
Excess tax benefit from stock-based compensation				0	0	0
Payments of acquisition-related contingent consideration				0	(2,000)	(6,200)
Payments of financing costs, including call premiums on extinguishment of debt				0	0	0
Net financing activities and advances (to) from consolidated affiliates				129,100	113,400	(39,800)
Net cash provided by (used in) financing activities				64,700	89,800	(46,000)
Effect of currency translation on cash				(1,300)	0	100
Net increase (decrease) in cash and cash equivalents				(12,000)	3,500	(600)
Cash and cash equivalents - beginning of period	17,600	17,600	17,600	17,600	14,100	14,700
Cash and cash equivalents - end of period				5,600	17,600	14,100
Eliminations [Member]
Condensed Consolidating Statements of Cash Flows [Line Items]
Net cash (used in) provided by operating activities				0	0	0
Cash flows (used in) provided by investing activities:
Cash paid for acquisitions, net of cash acquired				0	0	0
Proceeds from disposal of business, net of cash divested					0	0
Capital expenditures				0	0	0
Proceeds from sale of property and equipment				0	0	0
Payments for investments, net				0	0	0
Net cash used in investing activities				0	0	0
Cash flows provided by (used in) financing activities:
Proceeds from credit facilities				0	0	0
Repayments of credit facilities				0	0	0
(Repayments of) proceeds from senior notes, net				0	0
Repayments of other borrowings and capital lease obligations				0	0	0
Repurchase of common stock						0
Proceeds from stock-based awards, net of tax withholdings				0	0	0
Excess tax benefit from stock-based compensation				0	0	0
Payments of acquisition-related contingent consideration				0	0	0
Payments of financing costs, including call premiums on extinguishment of debt				0	0	0
Net financing activities and advances (to) from 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	0	0	0
Cash and cash equivalents - end of period				$ 0	$ 0	$ 0