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Summary of Significant Accounting Policies - Summary of Effective AFUDC Rate (Details) | 12 Months Ended
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Dec. 31, 2024 | Dec. 31, 2023 | Dec. 31, 2022
Avista Utilities [Member] |  |  |
Effective Rate On Allowance For Funds Used During Construction [Line Items] |  |  |
Effective state AFUDC rate | 7.03% | 7.03% | 7.12%
Alaska Electric Light & Power [Member] |  |  |
Effective Rate On Allowance For Funds Used During Construction [Line Items] |  |  |
Effective state AFUDC rate | 8.47% | 8.61% | 8.08%

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- Definition [Line Items] for Effective Rate On Allowance For Funds Used During Construction [Table] + References No definition available. + Details
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- Definition Effective rate, including composite rate, of cost of financing additions to qualifying regulated assets, commonly called allowance for funds used during construction. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Name Accounting Standards Codification -Topic 980 -SubTopic 835 -Section 25 -Paragraph 1 -Publisher FASB -URI https://asc.fasb.org/1943274/2147478698/980-835-25-1 Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef -Name Accounting Standards Codification -Topic 980 -SubTopic 835 -Section 45 -Paragraph 1 -Publisher FASB -URI https://asc.fasb.org/1943274/2147479123/980-835-45-1 + Details
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- Details
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