Retirement Benefits - Components of Net Periodic Benefit Cost (Credit) (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2025	Mar. 31, 2024
Pension Benefit Cost (Credit)
Defined Benefit Plan Disclosure [Line Items]
Service cost	$ 1,944	$ 2,165
Interest cost	8,119	8,413
Expected return on plan assets	(10,257)	(10,771)
Amortization of prior service cost	8	23
Amortization of actuarial losses (gains)	1,893	1,852
Net periodic benefit cost	1,707	1,682
Other Postretirement Benefit Credit
Defined Benefit Plan Disclosure [Line Items]
Service cost	4	7
Interest cost	151	165
Amortization of prior service cost	(15)	(5)
Amortization of actuarial losses (gains)	(86)	(84)
Net periodic benefit cost	$ 54	$ 83