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Committed Lines of Credit - Schedule of Balances Outstanding and Interest Rates of Borrowings (Details) - Avista Utilities [Member] - USD ($)
$ in Thousands
Mar. 31, 2022
Dec. 31, 2021
Short-term Debt [Line Items]    
Balance outstanding at end of period   $ 284,000
Letters of credit outstanding at end of period $ 29,288 $ 34,000
Average interest rate at end of period   1.11%