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Capitalization (Tables) | 9 Months Ended
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Sep. 30, 2025
Equity [Abstract] |
Schedule of Carrying Amount and Fair Value of First Mortgage Bonds (FMBs) | The carrying amount and fair value of the FMBs were as follows:
|  | (Thousands of Dollars)
|  | September 30, 2025 |  | December 31, 2024 |
|  | Carrying Amount |  | Fair Value |  | Carrying Amount |  | Fair Value |
FMBs |  | $ | 126,172 |  |  | $ | 125,545 |  |  | $ | 129,602 |  |  | $ | 125,067 |  |

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- Definition Tabular disclosure of the capitalization of the entity comprised of its long-term debt and equity instruments. The table may be detailed by subsidiary (legal entity) and include information by type of debt or equity detailed by instrument. + References No definition available. + Details
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