Quarterly report pursuant to Section 13 or 15(d)

Condensed Consolidated Balance Sheets (Unaudited) (Parenthetical)

 v2.3.0.11
Condensed Consolidated Balance Sheets (Unaudited) (Parenthetical) (USD $)
Jun. 30, 2011
Dec. 31, 2010
Stockholders' Equity :    
Convertible preferred stock, shares issued 0 0
Treasury stock, shares 15,272,525 14,980,640
Common Class A
   
Stockholders' Equity :    
Common stock, par value $ 0.01 $ 0.01
Common stock, shares authorized 100,000,000 100,000,000
Common stock, shares issued 56,214,480 55,738,639
Common stock, shares outstanding 40,941,955 40,757,999
Common Class B
   
Stockholders' Equity :    
Common stock, par value $ 0.01 $ 0.01
Common stock, shares authorized 30,000,000 30,000,000
Common stock, shares outstanding 12,029,375 12,029,375