Pension and Other Postretirement Plans (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2025	Sep. 30, 2024	Sep. 30, 2025	Sep. 30, 2024
Defined Benefit Plan Deferred Pension And Other Postretirement Benefit Plan Costs Recovered [Abstract]
Deferred (recognized) pension and OPEB costs		$ (500)	$ (700)	$ (3,100)
Pension Benefits [Member]
Components of net periodic benefit cost:
Service cost	$ 653	769	1,959	2,308
Interest cost	4,285	4,280	12,854	12,839
Expected return on assets	(7,254)	(7,149)	(21,761)	(21,448)
Amortization of:
Actuarial (gain) loss	75	215	225	644
Net periodic benefit (credit) cost	(2,241)	(1,885)	(6,723)	(5,657)
Postretirement Benefits [Member]
Components of net periodic benefit cost:
Service cost	186	214	557	642
Interest cost	757	778	2,271	2,354
Expected return on assets	(678)	(675)	(2,036)	(2,059)
Settlement cost	0	288	0	288
Amortization of:
Transition obligation	1	1	2	2
Prior service credit	0	(234)	0	(242)
Actuarial (gain) loss	(161)	774	(482)	568
Net periodic benefit (credit) cost	$ 105	$ 1,146	$ 312	$ 1,553