Debt instrument issued date.

No definition available.

Name:	ava_DebtInstrumentIssuedDate
Namespace Prefix:	ava_
Data Type:	xbrli:gYearItemType
Balance Type:	na
Period Type:	duration

- Definition

Percentage points added to the reference rate to compute the variable rate on the debt instrument.

+ References

No definition available.

+ Details

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Balance Type:	na
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- Definition

Description of reference rate used for variable rate of debt instrument.

+ References

No definition available.

+ Details

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Balance Type:	na
Period Type:	duration

- Definition

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

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
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-SubTopic 20
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+ Details

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Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

+ References

No definition available.

+ Details

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- Definition

The parent entity's interest in net assets of the subsidiary, expressed as a percentage.

+ References

No definition available.

+ Details

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- Definition

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.

+ References

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-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
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Long- Term Debt to Affiliated Trusts - Additional Information (Details) - USD ($) $ in Millions	1 Months Ended	9 Months Ended	12 Months Ended
	Jul. 31, 2023	Sep. 30, 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%
Trust Preferred Securities Subject to Mandatory Redemption [Member] \| 1997 Floating Rate Junior Subordinated Deferrable Interest Debentures, Series B [Member] \| SOFR [Member] \| Avista Capital II [Member] \| Forecast [Member]
Debt Instrument [Line Items]
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