Quanta Services, Inc. Quarterly report pursuant to Section 13 or 15(d)

Segment Information - Summarized Financial Information (Detail) (USD $) In Thousands, unless otherwise specified	3 Months Ended
	Mar. 31, 2015	Mar. 31, 2014
Segment Reporting Information [Line Items]
Revenues	$ 1,886,956us-gaap_SalesRevenueServicesNet	$ 1,762,574us-gaap_SalesRevenueServicesNet
Operating income (loss)	93,717us-gaap_OperatingIncomeLoss	90,495us-gaap_OperatingIncomeLoss
Depreciation	44,074us-gaap_Depreciation	36,865us-gaap_Depreciation
Electric Power Infrastructure [Member]
Segment Reporting Information [Line Items]
Revenues	1,225,743	1,278,168
Operating income (loss)	107,932	144,412
Depreciation	20,527	17,564
Oil and Gas Infrastructure Services [Member]
Segment Reporting Information [Line Items]
Revenues	621,094	445,857
Operating income (loss)	24,147	(21,172)
Depreciation	16,469	13,215
Fiber Optic Licensing and Other [Member]
Segment Reporting Information [Line Items]
Revenues	40,119	38,549
Operating income (loss)	11,532	12,109
Depreciation	5,066	4,318
Corporate and Non-Allocated Costs [Member]
Segment Reporting Information [Line Items]
Operating income (loss)	(49,894)	(44,854)
Depreciation	$ 2,012	$ 1,768