Stockholders' Equity (Share Count And Par Value Data Related To Stockholders' Equity) (Details) (USD $)	Mar. 31, 2012	Dec. 31, 2011	Apr. 02, 2011	Dec. 31, 2010
Stockholders' Equity [Abstract]
Preferred Stock, Par value per share	$ 0.01	$ 0.01
Preferred Stock, Shares authorized	10,000,000	10,000,000
Preferred Stock, Shares outstanding	0	0
Common Stock-Class A, Par value per share	$ 0.01	$ 0.01
Common Stock-Class A, Shares authorized	150,000,000	150,000,000
Common Stock-Class A, Shares issued	72,151,857	72,151,857
Common Stock-Class A, Shares outstanding	51,908,374	52,095,166	54,730,861	55,711,325
Treasury Stock, Shares held	20,243,483	20,056,691