Agreement expiration month and year.

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- Definition

IBEW chapter.

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No definition available.

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- Definition

Number of actions on behalf of individual plaintiffs.

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No definition available.

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- Definition

Number of collective bargaining agreement term.

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No definition available.

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- Definition

Number Of employees comprised.

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No definition available.

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- Definition

Number of plaintiffs.

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No definition available.

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Number of residential, commercial and other structures impacted.

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No definition available.

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Number of subrogation actions filed.

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No definition available.

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Percentage of employees represented.

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Percentage of largest group of employees represented.

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No definition available.

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Road fire covered area.

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No definition available.

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- Definition

The proportionate share of interest (percent) in a jointly owned utility plant.

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Amount awarded to other party in judgment or settlement of litigation.

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No definition available.

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- 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.

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Reference 1: http://www.xbrl.org/2003/role/disclosureRef
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The value (monetary amount) of the award the plaintiff seeks in the legal matter.

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The amount of cash paid for the settlement of litigation or for other legal issues during the period.

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Commitments and Contingencies - Additional Information (Details) $ in Millions		1 Months Ended		2 Months Ended	6 Months Ended
	Apr. 15, 2025 Employees Chapter	Jun. 30, 2025 USD ($) Plaintiff	Aug. 31, 2019 USD ($)	May 31, 2025 USD ($)	Jun. 30, 2025 USD ($) Lawsuit Plaintiff	Jul. 31, 2024	Aug. 31, 2023 a	Jan. 16, 2023	Sep. 30, 2020 a Structures
Collective Bargaining Agreements Avista Utilities Employees [Member] \| IBEW [Member]
Loss Contingencies [Line Items]
Percentage of employees represented					35.00%
Collective Bargaining Agreements Avista Utilities Bargaining Unit Employees [Member] \| IBEW [Member]
Loss Contingencies [Line Items]
Percentage of largest group of employees represented					90.00%
Collective Bargaining Agreements [Member] \| IBEW [Member]
Loss Contingencies [Line Items]
IBEW chapter \| Chapter	77
Agreement term					4 years
Agreement expiration month and year					2025-03
Number of employees comprised \| Employees	20
Boyds Fire [Member] \| Asplundh Tree Company and CN Utility Consulting [Member]
Loss Contingencies [Line Items]
Litigation settlement amount		$ 3.0
Boyds Fire [Member] \| Avista Corp [Member] \| Maximum [Member]
Loss Contingencies [Line Items]
Litigation settlement amount		$ 0.1
Boyds Fire [Member] \| Damage from Fire [Member] \| Maximum [Member]
Loss Contingencies [Line Items]
Loss contingency, damages sought, value			$ 4.0
Boyds Fire [Member] \| Property Damages [Member] \| Avista Corp [Member]
Loss Contingencies [Line Items]
Loss contingency, damages sought, value			1.0
Boyds Fire [Member] \| Insurance proceeds paid to their insureds [Member] \| Avista Corp [Member]
Loss Contingencies [Line Items]
Loss contingency, damages sought, value			$ 2.0
Babb Road Fire [Member] \| Damage from Fire [Member]
Loss Contingencies [Line Items]
Litigation settlement amount				$ 27.0
Number of residential, commercial and other structures impacted \| Structures									220
Road fire covered area \| a									15,000
Number of subrogation actions filed \| Lawsuit					6
Number of actions on behalf of individual plaintiffs \| Plaintiff					5
Number Of Plaintiffs \| Plaintiff		128			128
Babb Road Fire [Member] \| Damage from Fire [Member] \| CN Utility Consulting [Member]
Loss Contingencies [Line Items]
Litigation settlement amount				6.0
Babb Road Fire [Member] \| Damage from Fire [Member] \| Avista Corp [Member]
Loss Contingencies [Line Items]
Litigation settlement amount				$ 21.0
Orofino Fire [Member] \| Damage from Fire [Member]
Loss Contingencies [Line Items]
Road fire covered area \| a							53
Colstrip [Member]
Loss Contingencies [Line Items]
Settlement Amount					$ 1.0
Colstrip [Member] \| PSE [Member] \| Unit 4 [Member]
Loss Contingencies [Line Items]
Owners percentage interest		25.00%			25.00%	25.00%
Colstrip [Member] \| NorthWestern [Member] \| Unit 4 [Member]
Loss Contingencies [Line Items]
Owners percentage interest		30.00%			30.00%			15.00%