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

Business and Organization - Additional Information (Detail)

Business and Organization - Additional Information (Detail) (USD $) In Billions, unless otherwise specified	3 Months Ended		12 Months Ended
	Mar. 31, 2015 Entity Segment	Mar. 31, 2014	Dec. 31, 2014 Entity	Apr. 29, 2015
Organization And Description Of Business [Line Items]
Number of reportable segments	3us-gaap_NumberOfReportableSegments
Fiber Optic Licensing Terms, Minimum in years	5 years	5 years	5 years
Fiber Optic Licensing Terms, Maximum in years	25 years	25 years	25 years
Number of business acquisitions	3us-gaap_NumberOfBusinessesAcquired		9us-gaap_NumberOfBusinessesAcquired
Subsequent Event [Member]
Organization And Description Of Business [Line Items]
Sales price of fiber optic licensing operations				$ 1
Electric Power Infrastructure Services Business [Member] \| Canada [Member]
Organization And Description Of Business [Line Items]
Number of business acquisitions	1		4
Electric Power Infrastructure Services Business [Member] \| Australia [Member]
Organization And Description Of Business [Line Items]
Number of business acquisitions			1
Electric Power Infrastructure Services Business [Member] \| United States [Member]
Organization And Description Of Business [Line Items]
Number of business acquisitions			1
Oil and Gas Infrastructure Services Business [Member] \| Canada [Member]
Organization And Description Of Business [Line Items]
Number of business acquisitions	1		2
Oil and Gas Infrastructure Services Business [Member] \| Australia [Member]
Organization And Description Of Business [Line Items]
Number of business acquisitions	1
Oil and Gas Infrastructure Services Business [Member] \| United States [Member]
Organization And Description Of Business [Line Items]
Number of business acquisitions			1