Consolidated Statements of Comprehensive Income - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
NET EARNINGS (LOSS)	$ 41,222	$ 29,860	$ (19,628)
Other comprehensive income (loss), net of tax	(4)	(5)	(29)
Other Comprehensive Income (Loss), Foreign Currency Transaction and Translation Adjustment, Net of Tax	(336)	(1,059)	0
OTHER COMPREHENSIVE INCOME (LOSS):
Actuarial gain (loss) for retiree liabilities	(31,895)	(90,180)	130,330
Income tax (expense) or benefit	46	37	21
TOTAL COMPREHENSIVE INCOME (LOSS), net of tax	25,086	(23,198)	67,841
Pension Plans [Member]
Other comprehensive income (loss), net of tax	(16,111)	(50,119)	90,530
OTHER COMPREHENSIVE INCOME (LOSS):
Actuarial gain (loss) for retiree liabilities	(32,640)	(90,400)	129,856
Income tax (expense) or benefit	9,359	28,623	(51,622)
Post-Retirement Plans [Member]
Other comprehensive income (loss), net of tax	315	(1,875)	(3,032)
OTHER COMPREHENSIVE INCOME (LOSS):
Actuarial gain (loss) for retiree liabilities	745	220	474
Income tax (expense) or benefit	$ (180)	$ 1,071	$ 1,729