Consolidated Statements of Comprehensive Income - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Statement of Comprehensive Income [Abstract]
Net earnings	$ 32,295	$ 25,938	$ 29,678
Other comprehensive income :
Foreign currency translation adjustment	(328)	(847)	(1,721)
Pension and postretirement benefits, net of tax	1,473	(77)	(2,611)
Comprehensive income	$ 33,440	$ 25,014	$ 25,346