Stock-Based Compensation (Summary Of SAR Activity) (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended
	Mar. 31, 2019	Dec. 31, 2018
Stock Appreciation Rights [Roll Forward]
Outstanding, Shares	1,155,168	1,066,438
Granted, Shares	186,825
Forfeited, Shares	(1,479)
Expired, Shares	(682)
Exercised, Shares	(95,934)
Outstanding, Weighted Average Exercise Price, Beginning Balance	$ 40.22
Granted, Weighted Average Exercise Price	61.76
Forfeited, Weighted Average Exercise Price	51.16
Expired, Weighted Average Exercise Price	41.81
Exercised, Weighted Average Exercise Price	34.27
Outstanding, Weighted Average Exercise Price, Ending Balance	$ 44.19
Outstanding, Weighted Average Remaining Contractual Term (in years)	7 years 1 month
Outstanding, Aggregate Intrinsic Value, Ending Balance	$ 16,717