Stock-Based Compensation (Summary Of The Status Of Nonvested Share Awards) (Details) (USD $)	6 Months Ended
	Jun. 30, 2012
Nonvested Share Awards [Roll Forward]
Nonvested, Shares, Beginning Balance	653,782
Granted, Shares	217,535
Vested, Shares	(37,199)
Forfeited, Shares	(3,036)
Nonvested, Shares, Ending Balance	831,082
Nonvested, Weighted Average Grant Date Fair Value, Beginning Balance	$ 35.48
Granted , Weighted Average Grant Date Fair Value	$ 38.54
Vested , Weighted Average Grant Date Fair Value	$ 37.42
Forfeited , Weighted Average Grant Date Fair Value	$ 37.20
Nonvested , Weighted Average Grant Date Fair Value, Ending Balance	$ 36.20