Equity-Based Compensation (Summary Of SAR Activity) (Details) (USD $)	3 Months Ended
	Mar. 31, 2012
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares, Outstanding at beginning of year	1,702,650
Shares, Granted	0
Shares, Exercised	(48,561)
Shares, Forfeited	(1,663)
Shares, Outstanding at end of period	1,640,276
Shares, Exercisable at end of period	1,538,022
Weighted-Average Exercise Price, Outstanding at beginning of year	$ 40.43
Weighted-Average Exercise Price, Granted	$ 0.00
Weighted-Average Exercise Price, Exercised	$ 26.94
Weighted-Average Exercise Price, Forfeited	$ 36.36
Weighted-Average Exercise Price, Outstanding at end of period	$ 40.79
Weighted-Average Exercise Price, Exercisable at end of period	$ 41.18
Intrinsic value of exercised SARs	$ 545,701
Stock Option And Stock Appreciation Rights (SARs) [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares, Outstanding at beginning of year	1,287,724
Shares, Granted	0
Shares, Exercised	(17,343)
Shares, Forfeited	(10,665)
Shares, Outstanding at end of period	1,259,716
Shares, Exercisable at end of period	293,246
Weighted-Average Exercise Price, Outstanding at beginning of year	$ 28.91
Weighted-Average Exercise Price, Granted	$ 0.00
Weighted-Average Exercise Price, Exercised	$ 24.49
Weighted-Average Exercise Price, Forfeited	$ 34.45
Weighted-Average Exercise Price, Outstanding at end of period	$ 28.93
Weighted-Average Exercise Price, Exercisable at end of period	$ 23.37
Intrinsic value of exercised SARs	$ 269,978