Supplemental Financial Information - Components of Interest Expense (Net) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Supplemental Income Statement Elements [Abstract]
Interest on revolving credit facility	$ 7,378	$ 6,304	$ 5,115
Interest rate swap settlements	(200)	(247)	51
Line of credit fees	576	573	555
Debt issuance amortization costs	552	552	549
Interest on finance leases	127	172	169
Interest income	(1,610)	(804)	(379)
Other	46	79	71
Total interest expense, net	$ 6,869	$ 6,629	$ 6,131