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	$ 60,430	$ 46,018	$ 43,029
Other comprehensive income (loss), net of tax:
Foreign currency translation adjustments	(5,294)	(5,739)	(3,781)
Amortization of:
Prior service benefit	(54)	(112)	(3,017)
Unrecognized loss	763	2,261	2,435
Unrecognized actuarial gains (losses)	542	462	(413)
Plan settlement	0	654	0
Foreign currency exchange rate changes	3	(23)	(34)
Income tax (expense) benefit related to pension and postretirement plans	(514)	(1,325)	372
Pension and post retirement plans, net of tax	740	1,917	(657)
Total other comprehensive income (loss), net of tax	(4,554)	(3,822)	(4,438)
Comprehensive income	$ 55,876	$ 42,196	$ 38,591