Pensions and Other Post-retirement Benefits - Components of Net Periodic Benefit Cost (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2023	Jun. 30, 2022	Jun. 30, 2023	Jun. 30, 2022
Pension Benefits
Defined Benefit Plan Disclosure [Line Items]
Service cost	$ 1,884	$ 3,099	$ 3,768	$ 6,198
Interest cost	5,918	3,613	11,836	7,226
Expected return on plan assets	(9,906)	(12,418)	(19,812)	(24,836)
Amortization of prior service cost (credit)	37	36	74	72
Recognized net actuarial losses	47	3,018	94	6,036
Net periodic benefit (income) cost	(2,020)	(2,652)	(4,040)	(5,304)
Other Benefits
Defined Benefit Plan Disclosure [Line Items]
Service cost	53	82	106	164
Interest cost	273	148	546	296
Expected return on plan assets	0	0	0	0
Amortization of prior service cost (credit)	(61)	(84)	(122)	(168)
Recognized net actuarial losses	138	310	276	620
Net periodic benefit (income) cost	$ 403	$ 456	$ 806	$ 912