Postretirement Benefits - Pension Plan Cost (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2026	Mar. 31, 2025
Retirement Benefits [Abstract]
Service cost for benefits earned	$ 9,590	$ 8,862
Interest cost on benefit obligation	15,514	14,675
Expected return on plan assets	(19,889)	(20,069)
Prior service cost amortization	458	422
Net actuarial gain amortization	(67)	(654)
Settlement gain	0	(477)
Pension plan cost	$ 5,606	$ 2,759
Defined Benefit Plan, Net Periodic Benefit Cost (Credit) Excluding Service Cost, Statement of Income or Comprehensive Income [Extensible Enumeration]	Other Nonoperating Income (Expense)