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

Goodwill and Other Intangible Assets - Other Intangible Assets (Detail)

Goodwill and Other Intangible Assets - Other Intangible Assets (Detail) (USD $) In Thousands, unless otherwise specified	3 Months Ended
	Mar. 31, 2015	Dec. 31, 2014
Finite And Indefinite Lived Intangible Assets [Line Items]
Intangible assets subject to amortization	$ 508,655	$ 511,951
Accumulated Amortization	(261,100)	(255,858)
Intangible Assets, Net	247,555us-gaap_FiniteLivedIntangibleAssetsNet	256,093us-gaap_FiniteLivedIntangibleAssetsNet
Remaining Weighted Average Amortization Period in Years	11 years
Customer Relationships [Member]
Finite And Indefinite Lived Intangible Assets [Line Items]
Intangible assets subject to amortization	255,901	257,380
Accumulated Amortization	(77,968)	(74,289)
Intangible Assets, Net	177,933	183,091
Remaining Weighted Average Amortization Period in Years	10 years 2 months 12 days
Backlog [Member]
Finite And Indefinite Lived Intangible Assets [Line Items]
Intangible assets subject to amortization	149,307	151,404
Accumulated Amortization	(138,615)	(138,460)
Intangible Assets, Net	10,692	12,944
Remaining Weighted Average Amortization Period in Years	1 year 2 months 12 days
Trade Names [Member]
Finite And Indefinite Lived Intangible Assets [Line Items]
Intangible assets subject to amortization	49,806	49,664
Accumulated Amortization	(6,882)	(6,278)
Intangible Assets, Net	42,924	43,386
Remaining Weighted Average Amortization Period in Years	19 years 6 months
Non-compete Agreements [Member]
Finite And Indefinite Lived Intangible Assets [Line Items]
Intangible assets subject to amortization	31,329	31,430
Accumulated Amortization	(25,391)	(25,136)
Intangible Assets, Net	5,938	6,294
Remaining Weighted Average Amortization Period in Years	3 years 4 months 24 days
Patented Rights and Developed Technology [Member]
Finite And Indefinite Lived Intangible Assets [Line Items]
Intangible assets subject to amortization	22,312	22,073
Accumulated Amortization	(12,244)	(11,695)
Intangible Assets, Net	$ 10,068	$ 10,378
Remaining Weighted Average Amortization Period in Years	4 years 4 months 24 days