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Earnings Per Share (Schedule Of Diluted Earnings Per Share For Common And Class B Common Stock) (Details) (USD $)
3 Months Ended9 Months Ended
Sep. 30, 2011
Sep. 30, 2010
Sep. 30, 2011
Sep. 30, 2010
Earnings Per Share [Abstract]    
Diluted earnings per share for Common and Class B common stock$ 1.02$ 0.97$ 2.34$ 2.16