Quarterly report pursuant to Section 13 or 15(d)

Equity - Additional Information (Detail)

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Equity - Additional Information (Detail) (USD $)
 0 Months Ended 3 Months Ended 6 Months Ended
Mar. 31, 2013
Jun. 30, 2014
Jun. 30, 2013
Jun. 30, 2014
Jun. 30, 2013
Dec. 31, 2013
Equity [Line Items]            
Minimum number of shares that can be exchanged by exchangeable shareholders unless the number of remaining exchangeable shares registered in the name of the holder is less       50,000    
Number of shares of Common stock received for each exchangeable share       1    
Exchangeable shares exchanged for common stock 409,110          
Aggregate authorized amount of common stock to be repurchased       $ 500,000,000    
Reduction in net income as a result of non controlling interests   4,362,000 4,489,000 8,602,000 9,265,000  
Carrying value of the investments held by Quanta in variable interest entities   15,200,000   15,200,000   7,100,000
Distributions to non-controlling interests   0 3,900,000 500,000 9,300,000  
Carrying value of the investment held by noncontrolling interest in variable interest entities   15,227,000   15,227,000   7,131,000
Treasury Stock [Member]
            
Equity [Line Items]            
Treasury stock acquired   1,300,000        
Value of treasury stock acquired, cost method   45,000,000        
Series F Preferred Stock [Member]
            
Equity [Line Items]            
Number of preferred Stock issued to voting trust   1   1    
Common Stock Withheld for Settlement of Employee Tax Liabilities [Member] | Treasury Stock [Member]
            
Equity [Line Items]            
Treasury stock acquired       300,000 400,000  
Value of treasury stock acquired, cost method       $ 11,800,000 $ 11,900,000