Stock-Based Compensation (Summary Of SAR Activity) (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended
	Mar. 31, 2017	Dec. 31, 2016
Stock Appreciation Rights [Roll Forward]
Outstanding, Shares, Beginning Balance	1,255,371	1,324,954
Granted, Shares	165,873
Forfeited, Shares	(1,080)
Expired, Shares	(541)
Exercised, Shares	(233,835)
Outstanding, Weighted Average Exercise Price, Beginning Balance	$ 34.53
Granted, Weighted Average Exercise Price	57.53
Forfeited, Weighted Average Exercise Price	38.12
Expired, Weighted Average Exercise Price	34.79
Exercised, Weighted Average Exercise Price	30.34
Outstanding, Weighted Average Exercise Price, Ending Balance	$ 38.34
Outstanding, Weighted Average Remaining Contractual Term (in years)	6 years 8 months
Outstanding, Aggregate Intrinsic Value, Ending Balance	$ 22,592