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.

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
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Reference 2: http://www.xbrl.org/2009/role/commonPracticeRef
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Reference 3: http://www.xbrl.org/2003/role/disclosureRef
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Reference 4: http://www.xbrl.org/2003/role/disclosureRef
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Reference 5: http://www.xbrl.org/2003/role/disclosureRef
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Reference 6: http://www.xbrl.org/2003/role/disclosureRef
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Reference 7: http://www.xbrl.org/2003/role/exampleRef
-Topic 460
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Reference 8: http://www.xbrl.org/2003/role/disclosureRef
-Topic 450
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Reference 9: http://www.xbrl.org/2003/role/disclosureRef
-Topic 450
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Reference 10: http://www.xbrl.org/2003/role/disclosureRef
-Topic 460
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Reference 11: http://www.xbrl.org/2003/role/disclosureRef
-Topic 450
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Commitments and Contingencies - Additional Information (Details) $ in Millions		1 Months Ended	6 Months Ended
	Apr. 15, 2025 Employees Chapter	Aug. 31, 2023 USD ($) a	Jun. 30, 2026	Jul. 31, 2026 USD ($)
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 year			2029
Number of employees comprised \| Employees	20
Orofino Fire [Member] \| Damage from Fire [Member]
Loss Contingencies [Line Items]
Loss contingency, damages sought, value		$ 0.2
Road fire covered area \| a		53
Rathdrum, Idaho Natural Gas Incident [Member] \| Subsequent Event [Member]
Loss Contingencies [Line Items]
Estimate of liability related to claim				$ 1.3