Long- Term Debt to Affiliated Trust - Narrative (Details) - USD ($) $ in Millions	3 Months Ended	12 Months Ended
Mar. 31, 2022	Dec. 31, 2000
Debt Instrument [Line Items]
Payments for repurchase of trust preferred securities		$ 10.0
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	$ 51.5
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	$ 50.0
Debt instrument, description of variable rate basis	LIBOR
Debt instrument, basis spread on variable rate	0.875%
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	$ 1.5

Debt instrument issued date.

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Face (par) amount of debt instrument at time of issuance.

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The cash outflow to reacquire preferred stocks issued by a business trust or other special purpose entity, mainly established by a bank holding entity, to third party investors. The trust's assets are deeply subordinated debentures of the bank holding entity. Most trust preferred securities are subject to a mandatory redemption upon the repayment of the debentures.

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