Consolidated Statements of Comprehensive Income - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2016	Jun. 30, 2015	Jun. 30, 2016	Jun. 30, 2015
NET EARNINGS	$ 11,575	$ 10,784	$ 19,793	$ 19,893
Other comprehensive income (loss), net of tax	0	2	0	(4)
Other Comprehensive Income (Loss), Foreign Currency Transaction and Translation Adjustment, Net of Tax	53	144	310	(296)
OTHER COMPREHENSIVE INCOME (LOSS):
Income tax (expense) or benefit		43		46
TOTAL COMPREHENSIVE INCOME, net of tax	13,783	12,032	24,413	21,797
Pension Plans [Member]
Other comprehensive income (loss), net of tax	2,146	1,142	4,292	2,284
OTHER COMPREHENSIVE INCOME (LOSS):
Income tax (expense) or benefit	(1,222)	(651)	(2,444)	(1,302)
Post-Retirement Plans [Member]
Other comprehensive income (loss), net of tax	9	(40)	18	(80)
OTHER COMPREHENSIVE INCOME (LOSS):
Income tax (expense) or benefit	(5)	$ 23	(10)	46
Retained Earnings [Member]
OTHER COMPREHENSIVE INCOME (LOSS):
TOTAL COMPREHENSIVE INCOME, net of tax	$ 11,575		$ 19,793	$ 19,893