Pensions and Other Post-retirement Benefits - Components of Net Periodic Benefit Cost (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2023	Sep. 30, 2022
Pension Benefits
Defined Benefit Plan Disclosure [Line Items]
Service cost	$ 1,884	$ 3,099	$ 5,652	$ 9,297
Interest cost	5,918	3,613	17,754	10,839
Expected return on plan assets	(9,906)	(12,418)	(29,718)	(37,254)
Amortization of prior service cost (credit)	37	36	111	108
Recognized net actuarial losses	47	3,018	141	9,054
Net periodic benefit (income) cost	(2,020)	(2,652)	(6,060)	(7,956)
Other Benefits
Defined Benefit Plan Disclosure [Line Items]
Service cost	53	82	159	246
Interest cost	273	148	819	444
Expected return on plan assets	0	0	0	0
Amortization of prior service cost (credit)	(61)	(84)	(183)	(252)
Recognized net actuarial losses	138	310	414	930
Net periodic benefit (income) cost	$ 403	$ 456	$ 1,209	$ 1,368