Pensions and Other Post-retirement Benefits - Components of Net Periodic Benefit Cost (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2022	Mar. 31, 2021
Pension Benefits
Defined Benefit Plan Disclosure [Line Items]
Service cost	$ 3,099	$ 3,242
Interest cost	3,613	2,817
Expected return on plan assets	(12,418)	(9,147)
Amortization of prior service cost (credit)	36	66
Recognized net actuarial losses	3,018	4,421
Settlements	0	(1,879)
Net periodic benefit (income) cost	(2,652)	(480)
Other Benefits
Defined Benefit Plan Disclosure [Line Items]
Service cost	82	99
Interest cost	148	116
Expected return on plan assets	0	0
Amortization of prior service cost (credit)	(84)	(90)
Recognized net actuarial losses	310	399
Settlements	0	0
Net periodic benefit (income) cost	$ 456	$ 524