Stock-Based Compensation (Summary Of The Status Of Nonvested Share Awards) (Details) (USD $)	9 Months Ended
	Sep. 30, 2012
Nonvested Share Awards [Roll Forward]
Nonvested, Shares, Beginning Balance	653,782
Granted, Shares	225,782
Vested, Shares	(41,424)
Forfeited, Shares	(8,383)
Nonvested, Shares, Ending Balance	829,757
Nonvested, Weighted Average Grant Date Fair Value, Beginning Balance	$ 35.48
Granted , Weighted Average Grant Date Fair Value	$ 38.60
Vested , Weighted Average Grant Date Fair Value	$ 37.32
Forfeited , Weighted Average Grant Date Fair Value	$ 33.68
Nonvested , Weighted Average Grant Date Fair Value, Ending Balance	$ 36.26