Pensions and Other Post-retirement Benefits - Components of Net Periodic Benefit Cost (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2024	Sep. 30, 2023	Sep. 30, 2024	Sep. 30, 2023
Pension Benefits
Defined Benefit Plan Disclosure [Line Items]
Service cost	$ 2,315	$ 1,884	$ 6,945	$ 5,652
Interest cost	5,970	5,918	17,910	17,754
Expected return on plan assets	(10,812)	(9,906)	(32,436)	(29,718)
Amortization of prior service cost (credit)	37	37	111	111
Recognized net actuarial losses	282	47	846	141
Settlements			1,308	0
Net periodic benefit (income) cost	(2,208)	(2,020)	(5,316)	(6,060)
Other Benefits
Defined Benefit Plan Disclosure [Line Items]
Service cost	44	53	132	159
Interest cost	248	273	744	819
Expected return on plan assets	0	0	0	0
Amortization of prior service cost (credit)	(46)	(61)	(138)	(183)
Recognized net actuarial losses	115	138	345	414
Settlements			0	0
Net periodic benefit (income) cost	$ 361	$ 403	$ 1,083	$ 1,209