Accumulated Other Comprehensive (Loss) Income - Summary of Components of Other Comprehensive Loss (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Foreign currency transaction loss
Foreign currency transaction gain (loss)	$ 1,996	$ 395
AOCI Attributable to Parent, Net of Tax
Total accumulated other comprehensive (loss) income, beginning of period	(78,960)
Total accumulated other comprehensive (loss) income, end of period	(76,803)
Accumulated other comprehensive (loss) income
AOCI Attributable to Parent, Net of Tax
Total accumulated other comprehensive (loss) income, beginning of period	(78,960)	(93,194)
Gain (Loss) recognized in OCI, Net	1,139	752
Gain (Loss) reclassified from AOCI to income, Net	1,018	912
Total accumulated other comprehensive (loss) income, end of period	(76,803)	(91,530)
Changes in fair market value of hedges
Changes in AOCI, Gross
Gross, beginning of the period	289	116
Other Comprehensive Income (Loss), before Reclassifications, before Tax	1,157	1,042
Reclassification from Accumulated Other Comprehensive Income, Current Period, before Tax	(114)	150
Gross, ending balance	1,332	1,308
Changes in AOCI, Income tax (benefit)
Income tax (benefit), beginning of period	(105)	(42)
Income tax (benefit), Gain (Loss) recognized in OCI	(261)	(378)
Income tax (benefit), Gain (Loss) reclassified from AOCI to income	25	(54)
Income tax (benefit), ending of period	(341)	(474)
AOCI Attributable to Parent, Net of Tax
Total accumulated other comprehensive (loss) income, beginning of period	184	74
Gain (Loss) recognized in OCI, Net	896	664
Gain (Loss) reclassified from AOCI to income, Net	(89)	96
Total accumulated other comprehensive (loss) income, end of period	991	834
Changes in unrealized pension cost
Changes in AOCI, Gross
Gross, beginning of the period	(130,096)	(151,618)
Other Comprehensive Income (Loss), before Reclassifications, before Tax	0	0
Reclassification from Accumulated Other Comprehensive Income, Current Period, before Tax	1,424	1,296
Gross, ending balance	(128,672)	(150,322)
Changes in AOCI, Income tax (benefit)
Income tax (benefit), beginning of period	52,837	60,672
Income tax (benefit), Gain (Loss) recognized in OCI	0	0
Income tax (benefit), Gain (Loss) reclassified from AOCI to income	(317)	(480)
Income tax (benefit), ending of period	52,520	60,192
AOCI Attributable to Parent, Net of Tax
Total accumulated other comprehensive (loss) income, beginning of period	(77,259)	(90,946)
Gain (Loss) recognized in OCI, Net	0	0
Gain (Loss) reclassified from AOCI to income, Net	1,107	816
Total accumulated other comprehensive (loss) income, end of period	(76,152)	(90,130)
Cumulative translation adjustment
Changes in AOCI, Gross
Gross, beginning of the period	(1,985)	(2,414)
Other Comprehensive Income (Loss), before Reclassifications, before Tax	238	86
Reclassification from Accumulated Other Comprehensive Income, Current Period, before Tax	0	0
Gross, ending balance	(1,747)	(2,328)
Changes in AOCI, Income tax (benefit)
Income tax (benefit), beginning of period	100	92
Income tax (benefit), Gain (Loss) recognized in OCI	5	2
Income tax (benefit), Gain (Loss) reclassified from AOCI to income	0	0
Income tax (benefit), ending of period	105	94
AOCI Attributable to Parent, Net of Tax
Total accumulated other comprehensive (loss) income, beginning of period	(1,885)	(2,322)
Gain (Loss) recognized in OCI, Net	243	88
Gain (Loss) reclassified from AOCI to income, Net	0	0
Total accumulated other comprehensive (loss) income, end of period	$ (1,642)	$ (2,234)