Segment Information - Financial Data by Segment (Details) - USD ($) $ in Thousands	3 Months Ended
Mar. 31, 2018	Mar. 31, 2017	Dec. 31, 2017
Sales to external customers	$ 31,709	$ 27,745
Operating income	1,365	1,214
Interest expense, net	405	263
Other (income) expense, net	(13)	13
Consolidated income before income taxes	973	938
Assets	107,246		$ 114,730
United States
Sales to external customers	27,777	24,475
Operating income	1,116	1,130
Assets	97,372		104,431
Canada
Sales to external customers	1,552	1,391
Operating income	139	32
Assets	4,323		4,926
Europe
Sales to external customers	2,380	1,879
Operating income	110	$ 52
Assets	$ 5,551		$ 5,373

Sum of the carrying amounts as of the balance sheet date of all assets that are recognized. Assets are probable future economic benefits obtained or controlled by an entity as a result of past transactions or events.

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