Pensions and Other Post-retirement Benefits - Components of Net Periodic Benefit Cost (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2025	Jun. 30, 2024	Jun. 30, 2025	Jun. 30, 2024
Pension Benefits
Defined Benefit Plan Disclosure [Line Items]
Service cost	$ 2,007	$ 2,315	$ 4,001	$ 4,630
Interest cost	5,979	5,970	11,913	11,940
Expected return on plan assets	(12,005)	(10,812)	(24,010)	(21,624)
Amortization of prior service cost (credit)	32	37	64	74
Recognized net actuarial losses	197	282	394	564
Settlements	721	1,308	721	1,308
Net periodic benefit (income) cost	(3,069)	(900)	(6,917)	(3,108)
Other Benefits
Defined Benefit Plan Disclosure [Line Items]
Service cost	31	44	62	88
Interest cost	276	248	552	496
Expected return on plan assets	0	0	0	0
Amortization of prior service cost (credit)	0	(46)	0	(92)
Recognized net actuarial losses	163	115	326	230
Settlements	0	0	0	0
Net periodic benefit (income) cost	$ 470	$ 361	$ 940	$ 722