Short-Term Borrowings - Additional Information (Details) - USD ($)	6 Months Ended
	Jun. 30, 2025	Dec. 31, 2024
Avista Utilities [Member]
Short-term Debt [Line Items]
Line of credit facility, maximum borrowing capacity	$ 500,000,000
Line of credit facility, expiration date	2029-06
Line of credit facility, covenant terms, maximum debt to equity ratio	65.00%
Letters of credit outstanding	$ 5,000,000	$ 5,000,000
Avista Utilities [Member] | Letter of Credit [Member]
Short-term Debt [Line Items]
Principal amount	50,000,000
Letters of credit outstanding	8,000,000	$ 12,000,000
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%