Annual report pursuant to Section 13 and 15(d)

Equity - Additional Information (Detail)

v2.4.0.6
Equity - Additional Information (Detail) (USD $)
1 Months Ended 12 Months Ended 1 Months Ended 12 Months Ended 1 Months Ended 12 Months Ended 12 Months Ended
Aug. 31, 2011
Dec. 31, 2012
Dec. 31, 2011
Dec. 31, 2010
May 31, 2011
Limited Vote Common Stock [Member]
Dec. 31, 2011
Limited Vote Common Stock [Member]
Dec. 31, 2010
Limited Vote Common Stock [Member]
Vote
Aug. 31, 2011
Common Stock [Member]
Dec. 31, 2011
Common Stock [Member]
Dec. 31, 2010
Common Stock [Member]
Dec. 31, 2012
Series F Preferred Stock [Member]
Dec. 31, 2012
Common Stock Withheld for Settlement of Employee Tax Liabilities [Member]
Dec. 31, 2011
Common Stock Withheld for Settlement of Employee Tax Liabilities [Member]
Dec. 31, 2010
Common Stock Withheld for Settlement of Employee Tax Liabilities [Member]
Stockholders 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                        
Number of preferred Stock issued to voting trust                     1      
Number of Limited Vote Common Stock exchanged for common stock           (432,485) (229,808)   454,107 241,300        
Number of common stock shares received for each share of Common Stock converted         1.05                  
Fraction of vote Common Stockholders were allowed on all matters other than election of the Board             0.1              
Treasury stock acquired               8,133,329 8,133,329     370,007 299,804 243,821
Value of treasury stock acquired, cost method $ 149,500,000   $ 149,547,000                 $ 6,700,000 $ 6,600,000 $ 4,600,000
Aggregate authorized amount of common stock to be repurchased 150,000,000                          
Reduction in net income as a result of non controlling interests   16,027,000 11,901,000 2,381,000                    
Carrying value of the investments held by Quanta in variable interest entities   5,400,000 7,300,000                      
Distributions to noncontrolling interests   17,970,000 5,954,000 2,395,000                    
Carrying value of the investment held by noncontrolling interest in variable interest entities   $ 5,368,000 $ 7,311,000