Other Comprehensive Income (Loss) - After-tax Changes in Accumulated Other Comprehensive Loss (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning balance	$ 111,637	$ 87,861	$ 95,370	$ 128,688
Net current period change	(353)	2,564	(767)	(2,888)
Ending balance	120,658	95,345	120,658	95,345
Foreign currency translation adjustment
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning balance			(19,024)	(24,032)
Net current period change			(1,809)	(257)
Ending balance	(20,833)	(24,289)	(20,833)	(24,289)
Pension and post-retirement benefits plans
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning balance			(27,423)	(22,382)
Amortization of actuarial gain (loss)			2,094	(1,850)
Ending balance	(25,329)	(24,232)	(25,329)	(24,232)
Derivative instruments
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning balance			1,441	464
Net current period change			(1,052)	(781)
Ending balance	389	(317)	389	(317)
Accumulated other comprehensive income (loss)
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning balance	(45,420)	(51,402)	(45,006)	(45,950)
Ending balance	$ (45,773)	$ (48,838)	$ (45,773)	$ (48,838)