Pension and Other Post-Retirement Benefit Plans - Components of Net Periodic Benefit Cost (Details) - Pension Plan - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020
U.S. Pension and Other Post-Retirement Benefit Plans
Defined Benefit Plan Disclosure [Line Items]
Interest cost	$ 207	$ 281	$ 621	$ 843
Expected return on plan assets	(553)	(519)	(1,659)	(1,556)
Amortization of prior service cost	2	2	6	5
Recognized actuarial loss	70	74	210	223
Net (benefit) cost	(274)	(162)	(822)	(485)
Non-U.S. Pension Plan
Defined Benefit Plan Disclosure [Line Items]
Interest cost	160	210	483	618
Expected return on plan assets	(251)	(277)	(755)	(806)
Amortization of prior service cost	12	151	40	437
Recognized actuarial loss	239	12	721	36
Net (benefit) cost	$ 160	$ 96	$ 489	$ 285