Accumulated Other Comprehensive Income (Loss) (Details) - USD ($) $ in Thousands, shares in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019	Mar. 31, 2020	Dec. 31, 2019	Mar. 31, 2019	Dec. 31, 2018
Schedule of Accumulated Other Comprehensive Income [Line Items]
Accumulated Other Comprehensive Income (Loss), Foreign Currency Translation Adjustment, Net of Tax	$ (12)	$ (5)	$ (12)	$ (5)	$ (12)	$ (12)	$ (1,484)	$ (1,479)
Accumulated other comprehensive income (loss), beginning balance	(61,116)	(88,383)	(61,866)	(91,362)
Other comprehensive income (loss) before reclassifications:
Other Comprehensive Income (Loss), Foreign Currency Transaction and Translation Gain (Loss), before Reclassification and Tax		(4)		(11)
Other Comprehensive Income (Loss), Foreign Currency Transaction and Translation Reclassification Adjustment from AOCI, Realized upon Sale or Liquidation, before Tax		2,253		2,253
Other Comprehensive Income (Loss), Foreign Currency Translation Adjustment, Tax		(770)		(768)
Amounts reclassified from accumulated other comprehensive income:
Actuarial costs (reclassified to salaries, wages and benefits)	972	3,925	1,944	7,850
Income Tax (Expense) or Benefit	(222)	(1,386)	(444)	(2,325)
Other Comprehensive Income (Loss), Foreign Currency Transaction and Translation Adjustment, Net of Tax	0	1,479	0	1,474
Other comprehensive income (loss), net of tax		4,788
Accumulated other comprehensive income (loss), ending balance	(60,366)	(83,595)	(60,366)	(83,595)
Total comprehensive income (loss)	$ (104,176)	$ (21,813)	$ 34,079	$ 3,831
Equivalent shares not included in weighted average shares outstanding because they would be anti-dilutive	9.3	10.9	0.1	10.8
Accumulated Other Comprehensive Income (Loss) [Member]
Amounts reclassified from accumulated other comprehensive income:
Total comprehensive income (loss)	$ 750	$ 4,788	$ 1,500	$ 7,767
Pension Plans [Member]
Schedule of Accumulated Other Comprehensive Income [Line Items]
Accumulated other comprehensive income (loss), beginning balance	(60,426)	(86,091)	(61,152)	(89,042)
Amounts reclassified from accumulated other comprehensive income:
Actuarial costs (reclassified to salaries, wages and benefits)	941	3,882	1,882	7,764
Income Tax (Expense) or Benefit	(215)	(609)	(430)	(1,540)
Other comprehensive income (loss), net of tax	726	3,273	1,452	6,224
Accumulated other comprehensive income (loss), ending balance	(59,700)	(82,818)	(59,700)	(82,818)
Post-Retirement Plans [Member]
Schedule of Accumulated Other Comprehensive Income [Line Items]
Accumulated other comprehensive income (loss), beginning balance	(678)	(808)	(702)	(841)
Amounts reclassified from accumulated other comprehensive income:
Actuarial costs (reclassified to salaries, wages and benefits)	31	43	62	86
Income Tax (Expense) or Benefit	(7)	(7)	(14)	(17)
Other comprehensive income (loss), net of tax	24	36	48	69
Accumulated other comprehensive income (loss), ending balance	$ (654)	$ (772)	$ (654)	$ (772)