Accumulated Other Comprehensive Income (Loss) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Schedule of Accumulated Other Comprehensive Income [Line Items]
Accumulated Other Comprehensive Income (Loss), Foreign Currency Translation Adjustment, Net of Tax	$ (12)	$ (1,479)	$ (1,348)	$ (1,477)
Accumulated other comprehensive income (loss), beginning balance	(91,362)	(63,020)	(79,866)
Other comprehensive income (loss) before reclassifications:
Actuarial gain (loss) for retiree liabilities	20,800	(40,934)	3,179
Other Comprehensive Income (Loss), Foreign Currency Transaction and Translation Gain (Loss), before Reclassification and Tax	(18)	(171)	195
Other Comprehensive Income (Loss), Foreign Currency Transaction and Translation Reclassification Adjustment from AOCI, Realized upon Sale or Liquidation, before Tax	2,253
Other comprehensive income (loss), reclassification from AOCI, Pension and Other Postretirement Benefit Plans, plan curtailment, before tax			12,923
Other Comprehensive Income (Loss), Foreign Currency Translation Adjustment, Tax	(768)	40	(66)
Amounts reclassified from accumulated other comprehensive income:
Actuarial costs (reclassified to salaries, wages and benefits)	15,700	3,766	8,061
Negative prior service cost (reclassified to salaries, wages and benefits)			(51)
Income Tax (Expense) or Benefit	(9,239)	8,997	(7,461)
Other Comprehensive Income (Loss), Foreign Currency Transaction and Translation Adjustment, Net of Tax	1,467	(131)	129
Other comprehensive income (loss), net of tax		(28,342)	16,846
Accumulated other comprehensive income (loss), ending balance	(61,866)	(91,362)	(63,020)
Total comprehensive income (loss)	90,698	40,943	35,341
Pension Plans [Member]
Schedule of Accumulated Other Comprehensive Income [Line Items]
Accumulated other comprehensive income (loss), beginning balance	(89,042)	(60,575)	(77,088)
Other comprehensive income (loss) before reclassifications:
Actuarial gain (loss) for retiree liabilities	20,793	(41,051)	3,116
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)	15,528	3,547	7,778
Income Tax (Expense) or Benefit	(8,431)	9,037	(7,304)
Other comprehensive income (loss), net of tax	27,890	(28,467)	16,513
Accumulated other comprehensive income (loss), ending balance	(61,152)	(89,042)	(60,575)
Post-Retirement Plans [Member]
Schedule of Accumulated Other Comprehensive Income [Line Items]
Accumulated other comprehensive income (loss), beginning balance	(841)	(1,097)	(1,301)
Other comprehensive income (loss) before reclassifications:
Actuarial gain (loss) for retiree liabilities	7	117	63
Amounts reclassified from accumulated other comprehensive income:
Actuarial costs (reclassified to salaries, wages and benefits)	172	219	283
Negative prior service cost (reclassified to salaries, wages and benefits)			(51)
Income Tax (Expense) or Benefit	(40)	(80)	(91)
Other comprehensive income (loss), net of tax	139	256	204
Accumulated other comprehensive income (loss), ending balance	$ (702)	$ (841)	$ (1,097)