CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME [Abstract]
Net earnings	$ 37,976	$ 60,430	$ 46,018
Other comprehensive income (loss), net of tax:
Foreign currency translation adjustments	7,027	(5,294)	(5,739)
Amortization of:
Prior service benefit	0	(54)	(112)
Unrecognized (gain) loss	(661)	763	2,261
Unrecognized actuarial gains	481	542	462
Plan settlement	0	0	654
Foreign currency exchange rate changes	0	3	(23)
Income tax related to pension and postretirement plans	72	(514)	(1,325)
Pension and post retirement plans, net of tax	(108)	740	1,917
Total other comprehensive income (loss), net of tax	6,919	(4,554)	(3,822)
Comprehensive income	$ 44,895	$ 55,876	$ 42,196