Accumulated Other Comprehensive Income (Loss) (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018	Dec. 31, 2018	Dec. 31, 2017
Schedule of Accumulated Other Comprehensive Income [Line Items]
Accumulated Other Comprehensive Income (Loss), Foreign Currency Translation Adjustment, Net of Tax	$ (1,484)	$ (1,364)	$ (1,479)	$ (1,348)
Accumulated other comprehensive income (loss), beginning balance	(91,362)	(63,020)
Other comprehensive income (loss) before reclassifications:
Other Comprehensive Income (Loss), Foreign Currency Transaction and Translation Gain (Loss), before Reclassification and Tax	(7)	(25)
Other Comprehensive Income (Loss), Foreign Currency Translation Adjustment, Tax	2	9
Amounts reclassified from accumulated other comprehensive income:
Actuarial costs (reclassified to salaries, wages and benefits)	3,925	942
Income Tax (Expense) or Benefit	(939)	(204)
Other Comprehensive Income (Loss), Foreign Currency Transaction and Translation Adjustment, Net of Tax	(5)	(16)
Accumulated other comprehensive income (loss), ending balance	(88,383)	(62,307)
Total comprehensive income (loss)	25,644	16,591
Pension Plans [Member]
Schedule of Accumulated Other Comprehensive Income [Line Items]
Accumulated other comprehensive income (loss), beginning balance	(89,042)	(60,575)
Amounts reclassified from accumulated other comprehensive income:
Actuarial costs (reclassified to salaries, wages and benefits)	3,882	887
Income Tax (Expense) or Benefit	(931)	(200)
Other comprehensive income (loss), net of tax	2,951	687
Accumulated other comprehensive income (loss), ending balance	(86,091)	(59,888)
Post-Retirement Plans [Member]
Schedule of Accumulated Other Comprehensive Income [Line Items]
Accumulated other comprehensive income (loss), beginning balance	(841)	(1,097)
Amounts reclassified from accumulated other comprehensive income:
Actuarial costs (reclassified to salaries, wages and benefits)	43	55
Income Tax (Expense) or Benefit	(10)	(13)
Other comprehensive income (loss), net of tax	33	42
Accumulated other comprehensive income (loss), ending balance	$ (808)	$ (1,055)