Consolidated Statements of Comprehensive Income - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2017	Mar. 31, 2016
NET EARNINGS	$ 9,988	$ 8,218
Other Comprehensive Income (Loss), Foreign Currency Transaction and Translation Adjustment, Net of Tax	37	257
OTHER COMPREHENSIVE INCOME:
TOTAL COMPREHENSIVE INCOME, NET OF TAXES	11,296	10,630
Pension Plans [Member]
Other comprehensive income, net of tax	1,234	2,146
OTHER COMPREHENSIVE INCOME:
Income tax (expense) or benefit	(703)	(1,222)
Post-Retirement Plans [Member]
Other comprehensive income, net of tax	37	9
OTHER COMPREHENSIVE INCOME:
Income tax (expense) or benefit	$ (21)	$ (5)