Supplemental Financial Information (Interest Expense) (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020
Supplemental Income Statement Elements [Abstract]
Interest on revolving credit facility	$ 5	$ 1,388	$ 106	$ 2,467
Interest rate swap settlements	0	336	0	422
Line of credit fees	291	152	564	318
Debt issuance amortization costs	179	138	358	276
Interest on finance leases	47	32	259	65
Interest income	(150)	(269)	(345)	(589)
Other	32	2	69	27
Total interest expense, net	$ 404	$ 1,779	$ 1,011	$ 2,986