Stock-Based Compensation (Schedule Of Stock Option Activity) (Details) (USD $) In Thousands, except Share data, unless otherwise specified	12 Months Ended
	Dec. 31, 2011 years
Stock-Based Compensation [Abstract]
Outstanding at January 1, 2011	1,134,915
Shares, Granted
Shares, Exercised	(795,915)
Shares, Forfeited
Outstanding at December 31, 2011	339,000
Vested and expected to vest at December 31, 2011	339,000
Exercisable at December 31, 2011	307,750
Weighted Average Exercise Price, Outstanding at January 1, 2011	$ 28.46
Weighted Average Exercise price, Granted
Weighted Average Exercise price, Exercised	$ 27.43
Weighted Average Exercise price, Forfeited
Weighted Average Exercise Price, Outstanding at December 31, 2011	$ 30.86
Weighted Average Exercise Price, Vested and expected to vest at December 31, 2011	$ 30.86
Weighted Average Exercise price, Exercisable at December 31, 2011	$ 30.44
Weighted Average Remaining Contractual Term, Outstanding at January 1, 2011	1.3
Weighted Average Remaining Contractual Term, Outstanding at December 31, 2011	1.5
Weighted Average Remaining Contractual Term, Vested and expected to vest at December 31, 2011	1.5
Weighted Average Remaining Contractual Term, Exercisable at December 31, 2011	1.4
Aggregate Intrinsic Value, Average Intrinsic Value, Outstanding at January 1, 2011	$ 54,524
Aggregate Intrinsic Value, Average Intrinsic Value, Outstanding at December 31, 2011	11,533
Aggregate Intrinsic Value, Average Intrinsic Value, Vested and expected to vest at December 31, 2011	11,533
Aggregate Intrinsic Value, Average Intrinsic Value, Exercisable at December 31, 2011	$ 10,599