Defined Benefit Pension Plans - Schedule of Defined Benefit Plans Disclosures (Details) - Pension Plan - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020
Defined Benefit Plan Disclosure [Line Items]
Service cost	$ 316	$ 311	$ 619	$ 631
Interest cost	2,857	4,097	5,675	8,238
Expected return on assets	(6,350)	(6,945)	(12,620)	(13,963)
Amortization of actuarial loss	2,529	2,614	5,171	5,234
Net periodic (benefit)/cost	$ (648)	$ 77	$ (1,155)	$ 140