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 |
| X | ||||||||||
- Definition Amount before allocation of valuation allowances of deferred tax asset attributable to deductible temporary differences from advances and contributions. No definition available.
|
| X | ||||||||||
- Definition Deferred Tax Assets, Tax Deferred Expense, Compensation and Benefits, Pensions and Postretirement Benefits No definition available.
|
| X | ||||||||||
- Definition Deferred Tax Liabilities, Deferred Gain and Other-Property Related No definition available.
|
| X | ||||||||||
- Definition Deferred Tax Liabilities, Pension and Postretirement Benefits No definition available.
|
| X | ||||||||||
- Definition Deferred Tax Liabilities, Regulatory Asset, Debt Premium No definition available.
|
| X | ||||||||||
- Definition Deferred Tax Liability, Tax Related Regulatory Asset No definition available.
|
| X | ||||||||||
- Definition Amount of deferred tax liability attributable to taxable temporary differences. Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
|
| X | ||||||||||
- Definition Amount before allocation of valuation allowances of deferred tax asset attributable to deductible temporary differences from deferred income. Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
|
| X | ||||||||||
- Definition Amount before allocation of valuation allowances of deferred tax asset attributable to deductible temporary differences and carryforwards. Reference 1: http://www.xbrl.org/2003/role/disclosureRef
|
| X | ||||||||||
- References No definition available.
|
| X | ||||||||||
- Definition Amount, before allocation of valuation allowance, of deferred tax asset attributable to deductible temporary differences, classified as other. Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
|
| X | ||||||||||
- Definition Amount before allocation of valuation allowances of deferred tax asset attributable to deductible temporary differences derived regulatory assets and liabilities. Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
|
| X | ||||||||||
- Definition Amount before allocation of valuation allowances of deferred tax asset attributable to deductible temporary differences from state taxes. Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
|
| X | ||||||||||
- Definition Amount before allocation of valuation allowances of deferred tax asset attributable to deductible general business tax credit carryforwards. Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
|
| X | ||||||||||
- Definition Amount before allocation of valuation allowances of deferred tax asset attributable to deductible temporary differences from the unearned premiums reserve. Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
|
| X | ||||||||||
- Definition Amount, after deferred tax asset, of deferred tax liability attributable to taxable differences without jurisdictional netting. Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
|
| X | ||||||||||
- References No definition available.
|
| X | ||||||||||
- Definition Amount of deferred tax liability attributable to taxable temporary differences from intangible assets other than goodwill. Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
|
| X | ||||||||||
- Definition Amount of deferred tax liability attributable to taxable temporary differences classified as other. Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
|
| X | ||||||||||
- Definition Amount of deferred tax liability attributable to taxable temporary differences from property, plant, and equipment. Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
|
| X | ||||||||||
- Definition Amount of deferred tax liability attributable to taxable temporary differences from tax deferred revenue or income classified as other. Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
|