Consolidated Statements of Comprehensive Income - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Net income	$ 31,184	$ 26,191	$ 23,675
Company sponsored benefit plans:
Change in translation adjustment and post-employment benefits of equity method investments, net of tax benefit of $6, $36, and $37, respectively	(7)	42	(15)
Other comprehensive income (loss)	127	232	(728)
Comprehensive income	31,311	26,423	22,947
Change in Pension Plans [Member]
Company sponsored benefit plans:
Change in pension plans and post employment benefits, net of tax expense	0	244	133
Change in Post-employment Benefits [Member]
Company sponsored benefit plans:
Change in pension plans and post employment benefits, net of tax expense	$ 134	$ (54)	$ (846)