Accumulated Other Comprehensive Income (Loss) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	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	$ (1,348)	$ (1,477)	$ (1,395)	$ (1,059)
Accumulated other comprehensive income (loss), beginning balance	(79,866)	(99,012)	(82,876)
Other comprehensive income (loss) before reclassifications:
Actuarial gain (loss) for retiree liabilities	3,179	18,818	(31,895)
Other Comprehensive Income (Loss), Foreign Currency Transaction and Translation Gain (Loss), before Reclassification and Tax	195	(126)	(517)
Other comprehensive income (loss), reclassification from AOCI, Pension and Other Postretirement Benefit Plans, plan curtailment, before tax	12,923	(1,997)
Other Comprehensive Income (Loss), Foreign Currency Translation Adjustment, Tax	(66)	44	181
Amounts reclassified from accumulated other comprehensive income:
Actuarial costs (reclassified to salaries, wages and benefits)	8,061	13,632	7,462
Negative prior service cost (reclassified to salaries, wages and benefits)	(51)	(103)	(542)
Hedging gain (reclassified to interest expense)			(50)
Income Tax (Expense) or Benefit	0	0	46
Income Tax (Expense) or Benefit	(7,461)	(11,078)	9,406
Other comprehensive income (loss), net of tax	0	0	(4)
Other Comprehensive Income (Loss), Foreign Currency Transaction and Translation Adjustment, Net of Tax	129	(82)	(336)
Other comprehensive income (loss), net of tax		19,146	(16,136)
Accumulated other comprehensive income (loss), ending balance	(63,020)	(79,866)	(99,012)
Total comprehensive income (loss)	35,341	42,634	25,086
Pension Plans [Member]
Schedule of Accumulated Other Comprehensive Income [Line Items]
Accumulated other comprehensive income (loss), beginning balance	(77,088)	(97,302)	(81,191)
Other comprehensive income (loss) before reclassifications:
Actuarial gain (loss) for retiree liabilities	3,116	18,424	(32,640)
Other comprehensive income (loss), reclassification from AOCI, Pension and Other Postretirement Benefit Plans, plan curtailment, before tax	12,923
Amounts reclassified from accumulated other comprehensive income:
Actuarial costs (reclassified to salaries, wages and benefits)	7,778	13,472	7,170
Income Tax (Expense) or Benefit	(7,304)	(11,682)	9,359
Other comprehensive income (loss), net of tax	16,513	20,214	(16,111)
Accumulated other comprehensive income (loss), ending balance	(60,575)	(77,088)	(97,302)
Post-Retirement Plans [Member]
Schedule of Accumulated Other Comprehensive Income [Line Items]
Accumulated other comprehensive income (loss), beginning balance	(1,301)	(315)	(630)
Other comprehensive income (loss) before reclassifications:
Actuarial gain (loss) for retiree liabilities	63	394	745
Other comprehensive income (loss), reclassification from AOCI, Pension and Other Postretirement Benefit Plans, plan curtailment, before tax	0	(1,997)
Amounts reclassified from accumulated other comprehensive income:
Actuarial costs (reclassified to salaries, wages and benefits)	283	160	292
Negative prior service cost (reclassified to salaries, wages and benefits)	(51)	(103)	(542)
Income Tax (Expense) or Benefit	(91)	560	(180)
Other comprehensive income (loss), net of tax	204	(986)	315
Accumulated other comprehensive income (loss), ending balance	(1,097)	(1,301)	(315)
Derivative [Member]
Schedule of Accumulated Other Comprehensive Income [Line Items]
Accumulated other comprehensive income (loss), beginning balance	0	0	4
Amounts reclassified from accumulated other comprehensive income:
Accumulated other comprehensive income (loss), ending balance	$ 0	$ 0	$ 0