Consolidated Statements of Comprehensive Income - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018
NET EARNINGS	$ (26,601)	$ 24,634	$ (3,936)	$ 40,512
Other Comprehensive Income (Loss), Foreign Currency Transaction and Translation Adjustment, Net of Tax	1,479	(123)	1,474	(139)
OTHER COMPREHENSIVE INCOME (LOSS):
TOTAL COMPREHENSIVE INCOME, net of tax	(21,813)	25,240	3,831	41,831
Pension Plans [Member]
Other comprehensive income (loss), net of tax	3,273	687	6,224	1,374
OTHER COMPREHENSIVE INCOME (LOSS):
Income tax (expense) or benefit	(609)	(200)	(1,540)	(400)
Post-Retirement Plans [Member]
Other comprehensive income (loss), net of tax	36	42	69	84
OTHER COMPREHENSIVE INCOME (LOSS):
Income tax (expense) or benefit	(7)	(13)	(17)	(26)
Retained Earnings [Member]
NET EARNINGS		$ 24,634
OTHER COMPREHENSIVE INCOME (LOSS):
TOTAL COMPREHENSIVE INCOME, net of tax	$ (26,601)		$ (3,936)	$ 40,512