Quarterly report pursuant to Section 13 or 15(d)

Document and Entity Information

Document and Entity Information
9 Months Ended
Sep. 30, 2012
Oct. 31, 2012
Common Stock [Member]
Oct. 31, 2012
Exchangeable Shares [Member]
Entity Information [Line Items]      
Document Type 10-Q    
Amendment Flag false    
Document Period End Date Sep. 30, 2012    
Document Fiscal Year Focus 2012    
Document Fiscal Period Focus Q3    
Trading Symbol PWR    
Entity Registrant Name QUANTA SERVICES INC    
Entity Central Index Key 0001050915    
Current Fiscal Year End Date --12-31    
Entity Filer Category Large Accelerated Filer    
Entity Common Stock, Shares Outstanding   220,815,152 3,909,110