Pension and Other Post-Retirement Benefit Plans - Components of Net Periodic Benefit Cost (Details) - Pension Plan - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020
U.S. Pension and Other Post-Retirement Benefit Plans
Defined Benefit Plan Disclosure [Line Items]
Interest cost	$ 206	$ 281	$ 414	$ 562
Expected return on plan assets	(553)	(518)	(1,106)	(1,037)
Amortization of prior service cost	2	1	4	3
Recognized actuarial loss	66	75	140	149
Net (benefit) cost	(279)	(161)	(548)	(323)
Non-U.S. Pension Plan
Defined Benefit Plan Disclosure [Line Items]
Interest cost	162	204	323	408
Expected return on plan assets	(254)	(266)	(504)	(529)
Amortization of prior service cost	14	143	28	286
Recognized actuarial loss	243	13	482	24
Net (benefit) cost	$ 165	$ 94	$ 329	$ 189