Income Taxes - Schedule of Components of Deferred Tax Assets and Liabilities (Details) - USD ($) $ in Thousands	Dec. 31, 2025	Dec. 31, 2024
Deferred tax assets:
Advances and contributions	$ 28,183	$ 26,744
Unamortized investment tax credit	1,141	1,061
Pensions, postretirement benefits and stock-based compensation	11,749	12,529
Debt premium, net	2,734	3,446
California franchise tax	257	503
Deferred revenue	0	0
Tax related regulatory liability	22,572	23,112
Other	9,560	6,337
Total deferred tax assets	76,196	73,732
Deferred tax liabilities:
Utility plant	304,002	277,085
Pension and postretirement	9,272	9,068
Deferred gain and other-property	608	608
Regulatory asset - business combinations debt premium, net	2,734	3,446
Intangibles	2,193	2,443
Deferred revenue	2,330	1,418
Tax related regulatory asset	57,503	50,728
Other	5,447	4,979
Total deferred tax liabilities	384,089	349,775
Net deferred tax liabilities	$ 307,893	$ 276,043