Segment Information - Financial Data by Segment (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016	Dec. 31, 2016
Sales to external customers	$ 33,785	$ 31,913	$ 100,380	$ 98,198
Operating income (loss)	1,949	2,140	7,030	7,735
Interest expense, net	365	247	949	642
Other (income) expense, net	16	65	(44)	38
Consolidated income before income taxes	1,568	1,828	6,125	7,055
Assets	110,938		110,938		$ 92,066
United States
Sales to external customers	30,038	28,489	88,653	87,311
Operating income (loss)	1,709	1,974	6,084	7,165
Assets	101,420		101,420		84,104
Canada
Sales to external customers	1,661	1,585	5,556	5,623
Operating income (loss)	209	148	744	558
Assets	4,615		4,615		3,882
Europe
Sales to external customers	2,086	1,839	6,171	5,264
Operating income (loss)	31	$ 18	202	$ 12
Assets	$ 4,903		$ 4,903		$ 4,080