Other Comprehensive Loss - After-tax Changes in Accumulated Other Comprehensive Loss (Details) - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning balance	$ 67,690
Ending balance	78,434
Foreign currency translation adjustment
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning balance	(24,313)	$ (21,079)
Net current period change	5,209	215
Reclassification adjustments for losses reclassified into income	0	0
Ending balance	(19,104)	(20,864)
Pension and post-retirement benefits plans
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning balance	(24,532)	(18,575)
Net current period change	0	0
Reclassification adjustments for losses reclassified into income	(1,830)	(1,699)
Ending balance	(26,362)	(20,274)
Accumulated other comprehensive loss
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning balance	(48,845)	(39,654)
Net current period change	5,209	215
Reclassification adjustments for losses reclassified into income	(1,830)	(1,699)
Ending balance	$ (45,466)	$ (41,138)