Quarterly report pursuant to Section 13 or 15(d)

Equity (Details Textuals)

 v2.3.0.11
Equity (Details Textuals) (USD $)
 1 Months Ended 3 Months Ended 6 Months Ended
May 31, 2011
Jun. 30, 2011
Jun. 30, 2010
Jun. 30, 2011
Jun. 30, 2010
Dec. 31, 2010
Equity (Textuals) [Abstract]            
Number of shares of Common stock received for each exchangeable share   1   1    
Minimum number of shares that can be exchanged by exchangeable shareholders unless the total number of remaining exchangeable shares registered in the name of the holder is less   50,000   50,000    
Number of Series F preferred Stock issued to voting trust   1   1    
Fraction of vote Limited Vote Common Stockholders were allowed on all matters other than election of the Board     0.1   0.1 0.1
Number of common stock shares received for each share of Limited Vote Common Stock converted 1.05          
Common Stock outstanding   207,322,265   207,322,265   211,138,091
Number of Limited Vote Common Stock reclassified and converted for common stock   432,485   432,485    
Number of common stock shares issued on reclassification and conversion of limited vote common stock   454,107   454,107    
Number of Limited Vote Common Stock exchanged for common stock     229,808   229,808  
Number of common stock shares issued on exchange of limited vote common stock     241,300   241,300  
Aggregate authorized amount of common stock to be repurchased   $ 150,000,000        
Carrying value of the investments held by Quanta in variable interest entities   4,700,000   4,700,000   1,400,000
Noncontrolling interests   4,694,000   4,694,000   1,364,000
Net Income (Loss) Attributable to Noncontrolling Interests   2,512,000 337,000 3,801,000 693,000  
Common stock withheld for settlement of employee tax liabilities
            
Equity (Additional Textuals) [Abstract]            
Common stock repurchased       277,923 218,149  
Market value of common stock repurchased       6,200,000 4,200,000  
Common stock repurchased under repurchase plan
            
Equity (Additional Textuals) [Abstract]            
Common stock repurchased       4,915,225    
Market value of common stock repurchased       $ 94,466,000    
Limited Vote Common Stock, $.00001 par value, 0 and 3,345,333 shares authorized, and 0 and 432,485 shares issued and outstanding, respectively
            
Equity (Textuals) [Abstract]            
Common Stock outstanding   0   0   432,485