Segment Information - Financial Data by Segment (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020	Dec. 31, 2020
Sales to external customers	$ 44,847	$ 44,042	$ 88,372	$ 79,817
Operating income	3,789	4,383	6,757	6,392
Interest expense, net	(223)	(234)	(443)	(554)
Other income (expense), net	3,440	1	3,363	(37)
Consolidated income before income taxes	7,006	4,150	9,677	5,801
Assets	139,139		139,139		$ 129,868
United States Segment
Sales to external customers	36,840	38,476	72,888	68,922
Operating income	2,675	3,685	4,807	5,253
Assets	120,848		120,848		113,831
Canada Segment
Sales to external customers	3,990	2,381	7,322	4,800
Operating income	662	366	1,034	573
Assets	8,722		8,722		7,432
Europe Segment
Sales to external customers	4,017	3,185	8,162	6,095
Operating income	452	$ 332	916	$ 566
Assets	$ 9,569		$ 9,569		$ 8,605