Accumulated Other Comprehensive Income (Loss) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Schedule of Accumulated Other Comprehensive Income [Line Items]
Accumulated Other Comprehensive Income (Loss), Foreign Currency Translation Adjustment, Net of Tax	$ (1,477)	$ (1,395)	$ (1,059)
Accumulated other comprehensive income (loss), beginning balance	(99,012)	(82,876)	(29,818)
Other comprehensive income (loss) before reclassifications:
Actuarial gain (loss) for retiree liabilities	18,818	(31,895)	(90,180)
Other Comprehensive Income (Loss), Foreign Currency Transaction and Translation Gain (Loss), before Reclassification and Tax	(126)	(517)	(1,629)
Other comprehensive income (loss), reclassification from AOCI, Pension and Other Postretirement Benefit Plans, plan curtailment, before tax	(1,997)		11,660
Other Comprehensive Income (Loss), Foreign Currency Translation Adjustment, Tax	44	181	570
Amounts reclassified from accumulated other comprehensive income:
Actuarial costs (reclassified to salaries, wages and benefits)	13,632	7,462	319
Negative prior service cost (reclassified to salaries, wages and benefits)	(103)	(542)	(3,487)
Hedging gain (reclassified to interest expense)		(50)	(42)
Income Tax (Expense) or Benefit	0	46	37
Income Tax (Expense) or Benefit	(11,078)	9,406	30,301
Other comprehensive income (loss), net of tax	0	(4)	(5)
Other Comprehensive Income (Loss), Foreign Currency Transaction and Translation Adjustment, Net of Tax	(82)	(336)	(1,059)
Other comprehensive income (loss), net of tax		(16,136)	(53,058)
Accumulated other comprehensive income (loss), ending balance	(79,866)	(99,012)	(82,876)
Total comprehensive income (loss)	42,634	25,086	(23,198)
Pension Plans [Member]
Schedule of Accumulated Other Comprehensive Income [Line Items]
Accumulated other comprehensive income (loss), beginning balance	(97,302)	(81,191)	(31,072)
Other comprehensive income (loss) before reclassifications:
Actuarial gain (loss) for retiree liabilities	18,424	(32,640)	(90,400)
Other comprehensive income (loss), reclassification from AOCI, Pension and Other Postretirement Benefit Plans, plan curtailment, before tax			11,660
Amounts reclassified from accumulated other comprehensive income:
Actuarial costs (reclassified to salaries, wages and benefits)	13,472	7,170	(2)
Income Tax (Expense) or Benefit	(11,682)	9,359	28,623
Other comprehensive income (loss), net of tax	20,214	(16,111)	(50,119)
Accumulated other comprehensive income (loss), ending balance	(77,088)	(97,302)	(81,191)
Post-Retirement Plans [Member]
Schedule of Accumulated Other Comprehensive Income [Line Items]
Accumulated other comprehensive income (loss), beginning balance	(315)	(630)	1,245
Other comprehensive income (loss) before reclassifications:
Actuarial gain (loss) for retiree liabilities	394	745	220
Other comprehensive income (loss), reclassification from AOCI, Pension and Other Postretirement Benefit Plans, plan curtailment, before tax	(1,997)
Amounts reclassified from accumulated other comprehensive income:
Actuarial costs (reclassified to salaries, wages and benefits)	160	292	321
Negative prior service cost (reclassified to salaries, wages and benefits)	(103)	(542)	(3,487)
Income Tax (Expense) or Benefit	560	(180)	1,071
Other comprehensive income (loss), net of tax	(986)	315	(1,875)
Accumulated other comprehensive income (loss), ending balance	(1,301)	(315)	(630)
Derivative [Member]
Schedule of Accumulated Other Comprehensive Income [Line Items]
Accumulated other comprehensive income (loss), beginning balance	0	4	9
Amounts reclassified from accumulated other comprehensive income:
Accumulated other comprehensive income (loss), ending balance	$ 0	$ 0	$ 4