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Short-Term Borrowings - Additional Information (Details) - USD ($)
 3 Months Ended
Mar. 31, 2024
Dec. 31, 2023
Dec. 31, 2022
Avista Utilities [Member]      
Short-term Debt [Line Items]      
Line of credit facility, maximum borrowing capacity $ 500,000,000    
Line of credit facility, expiration date 2028-06    
Line of credit facility additional expiration period 2 years    
Line of credit facility, covenant terms, maximum debt to equity ratio 65.00%    
Line of credit, outstanding $ 212,200,000    
Letters of credit outstanding 6,700,000 $ 4,700,000  
Avista Utilities [Member] | Letter of Credit [Member]      
Short-term Debt [Line Items]      
Principal amount     $ 50,000,000
Letters of credit outstanding 14,000,000 20,000,000  
Alaska Electric Light & Power [Member]      
Short-term Debt [Line Items]      
Line of credit facility, maximum borrowing capacity $ 25,000,000    
Line of credit facility, expiration date 2028-06    
Line of credit facility, covenant terms, maximum debt to equity ratio 67.50%    
Line of credit, outstanding $ 0 $ 0