Consolidated Statements of Comprehensive Income - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
NET EARNINGS (LOSS)	$ (32,884)	$ 2,163	$ (76,622)	$ 21,956
Other Comprehensive Income (Loss), Foreign Currency Transaction and Translation Adjustment, Net of Tax	(15)	(256)	121	54
OTHER COMPREHENSIVE INCOME:
TOTAL COMPREHENSIVE INCOME (LOSS), NET OF TAXES	(27,099)	4,062	(68,158)	28,475
Pension Plans [Member]
Other comprehensive income, net of tax	5,763	2,146	8,232	6,438
OTHER COMPREHENSIVE INCOME:
Income tax (expense) or benefit	(3,283)	(1,222)	(4,689)	(3,666)
Post-Retirement Plans [Member]
Other comprehensive income, net of tax	37	9	111	27
OTHER COMPREHENSIVE INCOME:
Income tax (expense) or benefit	$ (21)	$ (5)	$ (63)	$ (15)