Stock-Based Compensation (Summary Of Restricted Stock Activity) (Details) $ / shares in Units, $ in Thousands	9 Months Ended
	Sep. 30, 2020 USD ($) $ / shares shares
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Period	3 years
Restricted Stock [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based Compensation Arrangement by Share-based Payment Award, Options, Vested in Period, Fair Value | $	$ 3,600
Share-based Payment Arrangement, Nonvested Award, Cost Not yet Recognized, Period for Recognition	1 year
Outstanding at January 1, 2020 | shares	1,101,781
Granted | shares	65,041
Vested | shares	(80,872)
Forfeited | shares	(70,884)
Outstanding at September 30, 2020 | shares	1,034,516
Outstanding at January 1, 2020 (non-vested), Weighted Average Grant Date Fair Value | $ / shares	$ 53.30
Granted, Weighted Average Grant Date Fair Value | $ / shares	35.26
Vesting and transfer of ownership to recipients, Weighted Average Grant Date Fair Value | $ / shares	$ 44.40
Converted from performance shares | shares	19,450
Forfeited, Weighted Average Grant Date Fair Value, per share | $ / shares	$ 53.51
Share-based Compensation Arrangements by Share-based Payment Award, Options, Other Share Increase (Decrease) in Period, Weighted Average Exercise Price | $ / shares	38.13
Outstanding at September 30, 2020 (non-vested), Weighted Average Grant Date Fair Value | $ / shares	$ 52.41
Aggregate Intrinsic Value | $	$ 20,390
Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Period	3 years
Restricted Stock Units (RSUs) [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Period	1 year