Accumulated Other Comprehensive (Loss) Income - Summary of Components of Other Comprehensive Loss (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2017	Mar. 31, 2016
Foreign currency transaction loss
Foreign currency transaction gain (loss)	$ 395	$ 231
AOCI Attributable to Parent, Net of Tax
Total accumulated other comprehensive (loss) income, beginning of period	(93,194)
Total accumulated other comprehensive (loss) income, end of period	(91,530)
Accumulated other comprehensive (loss) income
AOCI Attributable to Parent, Net of Tax
Total accumulated other comprehensive (loss) income, beginning of period	(93,194)	(99,005)
Gain (Loss) recognized in OCI, Net	752	(258)
Gain (Loss) reclassified from AOCI to income, Net	912	1,051
Total accumulated other comprehensive (loss) income, end of period	(91,530)	(98,212)
Changes in fair market value of hedges
Changes in AOCI, Gross
Gross, beginning of the period	116	(768)
Other Comprehensive Income (Loss), before Reclassifications, before Tax	1,042	242
Reclassification from Accumulated Other Comprehensive Income, Current Period, before Tax	150	231
Gross, ending balance	1,308	(295)
Changes in AOCI, Income tax (benefit)
Income tax (benefit), beginning of period	(42)	289
Income tax (benefit), Gain (Loss) recognized in OCI	(378)	(91)
Income tax (benefit), Gain (Loss) reclassified from AOCI to income	(54)	(88)
Income tax (benefit), ending of period	(474)	110
AOCI Attributable to Parent, Net of Tax
Total accumulated other comprehensive (loss) income, beginning of period	74	(479)
Gain (Loss) recognized in OCI, Net	664	151
Gain (Loss) reclassified from AOCI to income, Net	96	143
Total accumulated other comprehensive (loss) income, end of period	834	(185)
Changes in unrealized pension cost
Changes in AOCI, Gross
Gross, beginning of the period	(151,618)	(161,719)
Other Comprehensive Income (Loss), before Reclassifications, before Tax	0	0
Reclassification from Accumulated Other Comprehensive Income, Current Period, before Tax	1,296	1,451
Gross, ending balance	(150,322)	(160,268)
Changes in AOCI, Income tax (benefit)
Income tax (benefit), beginning of period	60,672	64,361
Income tax (benefit), Gain (Loss) recognized in OCI	0	0
Income tax (benefit), Gain (Loss) reclassified from AOCI to income	(480)	(543)
Income tax (benefit), ending of period	60,192	63,818
AOCI Attributable to Parent, Net of Tax
Total accumulated other comprehensive (loss) income, beginning of period	(90,946)	(97,358)
Gain (Loss) recognized in OCI, Net	0	0
Gain (Loss) reclassified from AOCI to income, Net	816	908
Total accumulated other comprehensive (loss) income, end of period	(90,130)	(96,450)
Cumulative translation adjustment
Changes in AOCI, Gross
Gross, beginning of the period	(2,414)	(1,279)
Other Comprehensive Income (Loss), before Reclassifications, before Tax	86	(406)
Reclassification from Accumulated Other Comprehensive Income, Current Period, before Tax	0	0
Gross, ending balance	(2,328)	(1,685)
Changes in AOCI, Income tax (benefit)
Income tax (benefit), beginning of period	92	111
Income tax (benefit), Gain (Loss) recognized in OCI	2	(3)
Income tax (benefit), Gain (Loss) reclassified from AOCI to income	0	0
Income tax (benefit), ending of period	94	108
AOCI Attributable to Parent, Net of Tax
Total accumulated other comprehensive (loss) income, beginning of period	(2,322)	(1,168)
Gain (Loss) recognized in OCI, Net	88	(409)
Gain (Loss) reclassified from AOCI to income, Net	0	0
Total accumulated other comprehensive (loss) income, end of period	$ (2,234)	$ (1,577)