Stock-Based Compensation (Summary of Stock-Based Compensation Expense) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Stock Options [Member]
Schedule Of Share Based Compensation Arrangements [Line Items]
Compensation expense recorded in selling, general and administrative expenses	$ 2,304	$ 1,801	$ 1,528
Deferred income tax benefits related to compensation expense	484	378	321
Total fair value of stock options vested	465	1,387	1,390
Unrecognized compensation cost	$ 2,039	$ 1,469	$ 606
Expected weighted-average recognition period for unrecognized compensation, in years	1 year 9 months 18 days	2 years 2 months 12 days	2 years 8 months 12 days
Performance Share Units [Member]
Schedule Of Share Based Compensation Arrangements [Line Items]
Compensation expense recorded in selling, general and administrative expenses	$ 3,270	$ 3,607	$ 4,152
Deferred income tax benefits related to compensation expense	773	757	872
Unrecognized compensation cost	$ 3,417	$ 2,730	$ 3,599
Expected weighted-average recognition period for unrecognized compensation, in years	1 year 6 months	1 year 7 months 6 days	1 year 4 months 24 days