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Short-Term Borrowings - Schedule of Balances Outstanding and Interest Rates of Borrowings (Details) - Avista Utilities [Member] - USD ($)
$ in Thousands
Dec. 31, 2023
Dec. 31, 2022
Short-term Debt [Line Items]    
Balance outstanding at end of period $ 349,000 $ 313,000
Letters of credit outstanding at end of period $ 4,700 $ 35,563
Average interest rate at end of period 6.46% 5.31%