Annual report pursuant to Section 13 and 15(d)

Document and Entity Information

Document and Entity Information (USD $)
In Billions, except Share data, unless otherwise specified
12 Months Ended
Dec. 31, 2012
Jun. 30, 2012
Feb. 20, 2013
Common Stock [Member]
Feb. 20, 2013
Exchangeable Shares [Member]
Entity Information [Line Items]        
Document Type 10-K      
Amendment Flag false      
Document Period End Date Dec. 31, 2012      
Document Fiscal Year Focus 2012      
Document Fiscal Period Focus FY      
Trading Symbol PWR      
Entity Registrant Name QUANTA SERVICES INC      
Entity Central Index Key 0001050915      
Current Fiscal Year End Date --12-31      
Entity Well-known Seasoned Issuer Yes      
Entity Current Reporting Status Yes      
Entity Voluntary Filers No      
Entity Filer Category Large Accelerated Filer      
Entity Common Stock, Shares Outstanding     209,333,557 3,909,110
Entity Public Float   $ 5.0