Consolidated Statements of Comprehensive Income - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Net income	$ 41,823	$ 31,184	$ 26,191
Company sponsored benefit plans:
Other, net of tax	(4)	(7)	42
Other comprehensive income	62	127	232
Comprehensive income	41,885	31,311	26,423
Pension Plans
Company sponsored benefit plans:
Change in pension plans and post employment benefits, net of tax expense	0	0	244
Post-employment benefits
Company sponsored benefit plans:
Change in pension plans and post employment benefits, net of tax expense	$ 66	$ 134	$ (54)