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Summary of Significant Accounting Policies - Summary of Effective AFUDC Rate (Details)
12 Months Ended
Dec. 31, 2022
Dec. 31, 2021
Dec. 31, 2020
Avista Utilities [Member]      
Effective Rate On Allowance For Funds Used During Construction [Line Items]      
Effective state AFUDC rate 7.12% 7.19% 7.25%
Alaska Electric Light & Power [Member]      
Effective Rate On Allowance For Funds Used During Construction [Line Items]      
Effective state AFUDC rate 8.08% 8.90% 8.04%