Accumulated Other Comprehensive Income (Loss) (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2016	Sep. 30, 2015	Jun. 30, 2016	Dec. 31, 2015	Jun. 30, 2015	Dec. 31, 2014
Schedule of Accumulated Other Comprehensive Income [Line Items]
Accumulated Other Comprehensive Income (Loss), Foreign Currency Translation Adjustment, Net of Tax	$ (1,341)	$ (1,410)	$ (1,341)	$ (1,410)	$ (1,085)	$ (1,395)	$ (1,355)	$ (1,059)
Accumulated other comprehensive income (loss), beginning balance	(94,392)	(80,972)	(99,012)	(82,876)
Other comprehensive income (loss) before reclassifications:
Other Comprehensive Income (Loss), Foreign Currency Transaction and Translation Gain (Loss), before Reclassification and Tax	(397)	(84)	75	(537)
Other Comprehensive Income (Loss), Foreign Currency Translation Adjustment, Tax	141	29	(21)	186
Amounts reclassified from accumulated other comprehensive income:
Actuarial costs (reclassified to salaries, wages and benefits)	3,408	1,866	10,224	5,598
Negative prior service cost (reclassified to salaries, wages and benefits)	(26)	(136)	(78)	(408)
Hedging gain (reclassified to interest expense)				(50)
Income Tax (Expense) or Benefit		0		46
Income Tax (Expense) or Benefit	(1,086)	(599)	(3,702)	(1,652)
Other comprehensive income (loss), net of tax	0	0	0	(4)
Other Comprehensive Income (Loss), Foreign Currency Transaction and Translation Adjustment, Net of Tax	(256)	(55)	54	(351)
Accumulated other comprehensive income (loss), ending balance	(92,493)	(79,925)	(92,493)	(79,925)
Total comprehensive income (loss)	4,062	7,608	28,475	29,405
Pension Plans [Member]
Schedule of Accumulated Other Comprehensive Income [Line Items]
Accumulated other comprehensive income (loss), beginning balance	(93,010)	(78,907)	(97,302)	(81,191)
Amounts reclassified from accumulated other comprehensive income:
Actuarial costs (reclassified to salaries, wages and benefits)	3,368	1,793	10,104	5,379
Income Tax (Expense) or Benefit	(1,222)	(651)	(3,666)	(1,953)
Other comprehensive income (loss), net of tax	2,146	1,142	6,438	3,426
Accumulated other comprehensive income (loss), ending balance	(90,864)	(77,765)	(90,864)	(77,765)
Post-Retirement Plans [Member]
Schedule of Accumulated Other Comprehensive Income [Line Items]
Accumulated other comprehensive income (loss), beginning balance	(297)	(710)	(315)	(630)
Amounts reclassified from accumulated other comprehensive income:
Actuarial costs (reclassified to salaries, wages and benefits)	40	73	120	219
Negative prior service cost (reclassified to salaries, wages and benefits)	(26)	(136)	(78)	(408)
Income Tax (Expense) or Benefit	(5)	23	(15)	69
Other comprehensive income (loss), net of tax	9	(40)	27	(120)
Accumulated other comprehensive income (loss), ending balance	(288)	(750)	(288)	(750)
Derivative [Member]
Schedule of Accumulated Other Comprehensive Income [Line Items]
Accumulated other comprehensive income (loss), beginning balance	0	0	0	4
Amounts reclassified from accumulated other comprehensive income:
Accumulated other comprehensive income (loss), ending balance	0	0	0	0
AOCI Attributable to Parent [Member]
Amounts reclassified from accumulated other comprehensive income:
Total comprehensive income (loss)	$ 1,899	$ 1,047	$ 6,519	$ 2,951