Segment Information - Financial Data by Segment (Details) - USD ($) $ in Thousands	3 Months Ended
Mar. 31, 2019	Mar. 31, 2018	Dec. 31, 2018
Sales to external customers	$ 31,370	$ 31,709
Operating income	1,534	1,365
Interest expense, net	501	405
Other income, net	(2)	(13)
Consolidated income before income taxes	1,035	973
Assets	110,615		$ 109,478
United States
Sales to external customers	27,439	27,777
Operating income	1,257	1,116
Assets	100,450		99,721
Canada
Sales to external customers	1,413	1,552
Operating income	135	139
Assets	4,294		3,839
Europe
Sales to external customers	2,518	2,380
Operating income	142	$ 110
Assets	$ 5,871		$ 5,918

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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