Long-Term Debt to Affiliated Trusts - Additional Information (Details) - USD ($) $ in Millions	1 Months Ended	6 Months Ended	12 Months Ended
	Jul. 31, 2023	Jun. 30, 2025	Dec. 31, 2000
Debt Instrument [Line Items]
Payments for repurchase of trust preferred securities			$ 10
1997 Floating Rate Junior Subordinated Deferrable Interest Debentures, Series B [Member] | Avista Capital II [Member]
Debt Instrument [Line Items]
Junior subordinated debenture issuance date		1997
Principal amount		$ 52
Avista Corp [Member]
Debt Instrument [Line Items]
Noncontrolling interest, ownership percentage by parent		100.00%
Trust Preferred Securities Subject to Mandatory Redemption [Member] | 1997 Floating Rate Junior Subordinated Deferrable Interest Debentures, Series B [Member] | Avista Capital II [Member]
Debt Instrument [Line Items]
Principal amount		$ 50
Debt instrument, basis spread on variable rate	1.137%
Debt Instrument, Variable Interest Rate, Type [Extensible Enumeration]	Secured Overnight Financing Rate (SOFR) Overnight Index Swap Rate [Member]
Common Trust Securities [Member] | 1997 Floating Rate Junior Subordinated Deferrable Interest Debentures, Series B [Member] | Avista Capital II [Member]
Debt Instrument [Line Items]
Principal amount		$ 2