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Regulatory Matters - Schedule of Regulatory Assets and Liabilities (Parenthetical) (Details) | 12 Months Ended
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Dec. 31, 2023 | Dec. 31, 2022 | Dec. 31, 2021 | Dec. 31, 2018 | Dec. 31, 2017
Regulated Asset Liability [Line Items] |  |  |  |  |
Federal statutory tax rate | 21.00% | 21.00% | 21.00% | 21.00% | 35.00%
Avista Utilities [Member] |  |  |  |  |
Regulated Asset Liability [Line Items] |  |  |  |  |
Tax cuts and jobs act period to return plant related excess deferred income taxes | 33 years |  |  |  |
Alaska Electric Light & Power [Member] |  |  |  |  |
Regulated Asset Liability [Line Items] |  |  |  |  |
Tax cuts and jobs act period to return plant related excess deferred income taxes | 22 years |  |  |  |

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