Accumulated Other Comprehensive Income (Loss) (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2017	Jun. 30, 2016	Mar. 31, 2017	Dec. 31, 2016	Mar. 31, 2016	Dec. 31, 2015
Schedule of Accumulated Other Comprehensive Income [Line Items]
Accumulated Other Comprehensive Income (Loss), Foreign Currency Translation Adjustment, Net of Tax	$ (1,341)	$ (1,085)	$ (1,341)	$ (1,085)	$ (1,440)	$ (1,477)	$ (1,138)	$ (1,395)
Accumulated other comprehensive income (loss), beginning balance	(78,558)	(96,600)	(79,866)	(99,012)
Other comprehensive income (loss) before reclassifications:
Other Comprehensive Income (Loss), Foreign Currency Transaction and Translation Gain (Loss), before Reclassification and Tax	152	80	210	472
Other Comprehensive Income (Loss), Foreign Currency Translation Adjustment, Tax	(53)	(27)	(74)	(162)
Amounts reclassified from accumulated other comprehensive income:
Actuarial costs (reclassified to salaries, wages and benefits)	2,008	3,408	4,016	6,816
Negative prior service cost (reclassified to salaries, wages and benefits)	(13)	(26)	(26)	(52)
Income tax expense	(776)	(1,254)	(1,521)	(2,616)
Other Comprehensive Income (Loss), Foreign Currency Transaction and Translation Adjustment, Net of Tax	99	53	136	310
Other comprehensive income, net of tax	1,371	2,208	2,679	4,620
Accumulated other comprehensive income (loss), ending balance	(77,187)	(94,392)	(77,187)	(94,392)
Total comprehensive income (loss)	(52,355)	13,783	(41,059)	24,413
Pension Plans [Member]
Schedule of Accumulated Other Comprehensive Income [Line Items]
Accumulated other comprehensive income (loss), beginning balance	(75,854)	(95,156)	(77,088)	(97,302)
Amounts reclassified from accumulated other comprehensive income:
Actuarial costs (reclassified to salaries, wages and benefits)	1,937	3,368	3,874	6,736
Income tax expense	(702)	(1,222)	(1,405)	(2,444)
Other comprehensive income, net of tax	1,235	2,146	2,469	4,292
Accumulated other comprehensive income (loss), ending balance	(74,619)	(93,010)	(74,619)	(93,010)
Post-Retirement Plans [Member]
Schedule of Accumulated Other Comprehensive Income [Line Items]
Accumulated other comprehensive income (loss), beginning balance	(1,264)	(306)	(1,301)	(315)
Amounts reclassified from accumulated other comprehensive income:
Actuarial costs (reclassified to salaries, wages and benefits)	71	40	142	80
Negative prior service cost (reclassified to salaries, wages and benefits)	(13)	(26)	(26)	(52)
Income tax expense	(21)	(5)	(42)	(10)
Other comprehensive income, net of tax	37	9	74	18
Accumulated other comprehensive income (loss), ending balance	$ (1,227)	$ (297)	$ (1,227)	$ (297)