Pension Plan and Other Postretirement Benefits (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2025	Mar. 31, 2024
Pension Plan
Pension Plan and Other Postretirement Benefits
Employer cash contributions	$ 2,300	$ 0
Estimated cash contributions in the current fiscal year	5,200
Components of the pension plans and other postretirement benefits
Service cost	5,207	5,648
Interest cost	9,553	8,881
Expected return on plan assets	(12,793)	(13,236)
Amortization of prior service cost	131	131
Recognized net actuarial (gain) loss	194	189
Net periodic benefit cost (credit)	2,292	1,613
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	1,408	1,520
Interest cost	1,773	1,684
Expected return on plan assets	(3,197)	(2,987)
Amortization of prior service cost	39	39
Recognized net actuarial (gain) loss	(522)	(198)
Net periodic benefit cost (credit)	$ (499)	$ 58