Pensions and Other Post-retirement Benefits - Components of Net Periodic Benefit Cost (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2025	Mar. 31, 2024
Pension Benefits
Defined Benefit Plan Disclosure [Line Items]
Service cost	$ 1,994	$ 2,315
Interest cost	5,934	5,970
Expected return on plan assets	(12,005)	(10,812)
Amortization of prior service cost (credit)	32	37
Recognized net actuarial losses	197	282
Net periodic benefit (income) cost	(3,848)	(2,208)
Other Benefits
Defined Benefit Plan Disclosure [Line Items]
Service cost	31	44
Interest cost	276	248
Expected return on plan assets	0	0
Amortization of prior service cost (credit)	0	(46)
Recognized net actuarial losses	163	115
Net periodic benefit (income) cost	$ 470	$ 361