Stock-Based Compensation (Summary Of SAR Activity) (Details) - USD ($) $ / shares in Units, $ in Thousands	9 Months Ended
	Sep. 30, 2020	Dec. 31, 2019
Stock Appreciation Rights [Roll Forward]
Outstanding, Shares	997,247	1,049,816
Granted, Shares	103,210
Forfeited, Shares	(5,600)
Expired, Shares	(150)
Exercised, Shares	(150,029)
Outstanding, Weighted Average Exercise Price, Beginning Balance	$ 43.55
Granted, Weighted Average Exercise Price	63.18
Forfeited, Weighted Average Exercise Price	58.15
Expired, Weighted Average Exercise Price	57.07
Exercised, Weighted Average Exercise Price	34.52
Outstanding, Weighted Average Exercise Price, Ending Balance	$ 46.86
Outstanding, Weighted Average Remaining Contractual Term (in years)	6 years 4 months 24 days
Outstanding, Aggregate Intrinsic Value, Ending Balance	$ 10,582