Supplemental Financial Information (Components of Interest Expense (Net)) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Supplemental Income Statement Elements [Abstract]
Interest on revolving credit facility	$ 3,294	$ 7,378	$ 6,304
Interest rate swap settlements	3,191	(200)	(247)
Line of credit fees	715	576	573
Debt issuance amortization costs	593	552	552
Interest on finance leases	134	127	172
Interest income	(939)	(1,610)	(804)
Other	147	46	79
Total interest expense, net	$ 7,135	$ 6,869	$ 6,629