Equity Compensation (Schedule Of Stock Options Granted, Forfeited, Exercised And Expired) (Details) (USD $) In Thousands, except Share data, unless otherwise specified	3 Months Ended
	Mar. 31, 2012 Y		Mar. 31, 2011
Equity Compensation [Abstract]
Number of Shares, Outstanding at beginning of period	1,765,881
Number of Shares, Granted	156,500		159,500
Number of Shares, Forfeited	0
Number of Shares, Exercised	(104,054)		(60,530)
Number of Shares, Expired	(1,734)
Number of Shares, Outstanding at end of period	1,816,593
Number of Shares, Exercisable at end of period	1,452,086
Weighted Average Exercise Price, Outstanding at beginning of period	$ 79.24
Weighted Average Exercise Price, Granted	$ 75.16
Weighted Average Exercise Price, Forfeited	$ 0.00
Weighted Average Exercise Price, Exercised	$ 44.86
Weighted Average Exercise Price, Expired	$ 17.25
Weighted Average Exercise Price, Outstanding at end of period	$ 80.91
Weighted Average Exercise Price, Exercisable at end of period	$ 80.10
Aggregate Exercise Price, Outstanding at beginning of period	$ 139,922
Aggregate Exercise Price, Granted	11,763
Aggregate Exercise Price, Forfeited	0
Aggregate Exercise Price, Exercised	(4,668)
Aggregate Exercise Price, Expired	(30)
Aggregate Exercise Price, Outstanding at end of period	146,987
Aggregate Exercise Price, Exercisable at end of period	116,310
Weighted Average Remaining Contractual Term, Outstanding at end of period, years	3.7
Weighted Average Remaining Contractual Term, Exercisable at end of period, years	3.1
Aggregate Intrinsic Value, Outstanding at end of period	11,047	[1]
Aggregate Intrinsic Value, Exercisable at end of period	$ 11,047	[1]

[1] The aggregate intrinsic value of the stock options was calculated by identifying those stock options that had a lower exercise price than the closing market price of our common stock on March 30, 2012 and multiplying the difference between the closing market price of our common stock and the exercise price of each of those stock options by the number of shares subject to those stock options that were outstanding or exercisable, as applicable.