Stock-Based Compensation (Summary Of SAR Activity) (Details) - USD ($) $ / shares in Units, $ in Thousands	9 Months Ended
	Sep. 30, 2017	Dec. 31, 2016
Stock Appreciation Rights [Roll Forward]
Outstanding, Shares	1,162,640	1,324,954
Granted, Shares	165,592
Forfeited, Shares	(9,448)
Expired, Shares	(837)
Exercised, Shares	(317,621)
Outstanding, Weighted Average Exercise Price, Beginning Balance	$ 34.53
Granted, Weighted Average Exercise Price	57.53
Forfeited, Weighted Average Exercise Price	44.25
Expired, Weighted Average Exercise Price	36.48
Exercised, Weighted Average Exercise Price	30.86
Outstanding, Weighted Average Exercise Price, Ending Balance	$ 38.73
Outstanding, Weighted Average Remaining Contractual Term (in years)	6 years 4 months
Outstanding, Aggregate Intrinsic Value, Ending Balance	$ 21,821