Stock-Based Compensation (Summary Of Restricted Stock Activity) (Details) (USD $)	3 Months Ended
	Mar. 31, 2012
Stock-Based Compensation [Abstract]
Unvested, Shares, Beginning Balance	2,542,989
Granted, Shares	1,113,500
Vested, Shares	0
Forfeited, Shares	(19,624)
Unvested, Shares, Ending Balance	3,636,865
Unvested, Weighted-Average Grant Date Fair Value Per Share, Beginning Balance	$ 21.67
Granted, Weighted-Average Grant Date Fair Value Per Share	$ 25.46
Vested, Weighted-Average Grant Date Fair Value Per Share	$ 0.00
Forfeited, Weighted-Average Grant Date Fair Value Per Share	$ 23.96
Unvested, Weighted-Average Grant Date Fair Value Per Share, Ending Balance	$ 22.82