Consolidated Statements of Comprehensive Income - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Consolidated Statements of Comprehensive Income [Abstract]
Net earnings	$ 55,972	$ 59,722	$ 52,826
Other comprehensive loss, net of tax:
Net foreign currency translation adjustment	(1,390)	(2,615)	(2,972)
Net change in postretirement benefit plan, net of taxes of $49, $72, and $56 at December 31, 2016, 2015, and 2014, respectively	(345)	152	123
Other comprehensive loss	(1,735)	(2,463)	(2,849)
Comprehensive income	$ 54,237	$ 57,259	$ 49,977