Pension Plan and Other Postretirement Benefits (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2026	Mar. 31, 2025
Pension Plan
Pension Plan and Other Postretirement Benefits
Employer cash contributions	$ 1,200	$ 2,300
Estimated cash contributions in the current fiscal year	2,700
Components of the pension plans and other postretirement benefits
Service cost	5,782	5,207
Interest cost	10,232	9,553
Expected return on plan assets	(14,276)	(12,793)
Amortization of prior service cost	131	131
Recognized net actuarial loss (gain)	606	194
Net periodic benefit cost (credit)	2,475	2,292
Other Benefits
Pension Plan and Other Postretirement Benefits
Employer cash contributions	0	0
Estimated cash contributions in the current fiscal year	0
Components of the pension plans and other postretirement benefits
Service cost	1,330	1,408
Interest cost	1,642	1,773
Expected return on plan assets	(3,679)	(3,197)
Amortization of prior service cost	39	39
Recognized net actuarial loss (gain)	(963)	(522)
Net periodic benefit cost (credit)	$ (1,631)	$ (499)