Other Income (expense) - (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Other Income And Expenses [Abstract]
Income from third party license fees	$ 339	$ 304
Foreign exchange (losses) gains, net	(1,478)	821
(Loss) gain on fixed asset disposals, net	5,410	2
Non-income tax refunds and other related credits	97	1,299
Pension and post retirement benefit income (costs), non-service components	124	(23,525)
Other operating income (expense), net	195	(76)
Total other income (expense), net	$ 4,687	$ (21,175)