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v3.21.2

Derivatives and Risk Management - Additional Information (Details) | 6 Months Ended | 12 Months Ended
--- | --- | ---
Jun. 30, 2021 MMBTU MWh | Dec. 31, 2020 MWh MMBTU
Canadian [Member] |  |
Derivative [Line Items] |  |
Number of days Canadian currency prices are settled with U.S. dollars | 60 days |
Purchase [Member] | Physical [Member] | Electric Derivative [Member] |  |
Derivative [Line Items] |  |
Expected deliveries of energy commodity derivatives after five years | MWh | 0 | 0
Purchase [Member] | Physical [Member] | Gas Derivative [Member] |  |
Derivative [Line Items] |  |
Expected deliveries of energy commodity derivatives after five years | MMBTU | 0 | 0
Purchase [Member] | Financial [Member] | Electric Derivative [Member] |  |
Derivative [Line Items] |  |
Expected deliveries of energy commodity derivatives after five years | MWh | 0 | 0
Purchase [Member] | Financial [Member] | Gas Derivative [Member] |  |
Derivative [Line Items] |  |
Expected deliveries of energy commodity derivatives after five years | MMBTU | 0 | 0
Sales [Member] | Physical [Member] | Electric Derivative [Member] |  |
Derivative [Line Items] |  |
Expected deliveries of energy commodity derivatives after five years | MWh | 0 | 0
Sales [Member] | Physical [Member] | Gas Derivative [Member] |  |
Derivative [Line Items] |  |
Expected deliveries of energy commodity derivatives after five years | MMBTU | 0 | 0
Sales [Member] | Financial [Member] | Electric Derivative [Member] |  |
Derivative [Line Items] |  |
Expected deliveries of energy commodity derivatives after five years | MWh | 0 | 0
Sales [Member] | Financial [Member] | Gas Derivative [Member] |  |
Derivative [Line Items] |  |
Expected deliveries of energy commodity derivatives after five years | MMBTU | 0 | 0

X
- Definition Energy commodity derivative expected to be settle after year five. + References No definition available. + Details
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Namespace Prefix: | ava_
Data Type: | xbrli:integerItemType
Balance Type: | na
Period Type: | duration

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- Definition Number of period currency prices are settled with domestic country currency. + References No definition available. + Details
Name: | ava_NumberOfPeriodCurrencyPricesAreSettledWithDomesticCountryCurrency
Namespace Prefix: | ava_
Data Type: | xbrli:durationItemType
Balance Type: | na
Period Type: | duration

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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. + References No definition available. + Details
Name: | us-gaap_DerivativeLineItems
Namespace Prefix: | us-gaap_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

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- Details
Name: | srt_StatementGeographicalAxis=country_CA
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_IncomeStatementLocationAxis=ava_PurchaseMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_DerivativeInstrumentRiskAxis=ava_PhysicalMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | srt_EnergyAxis=ava_ElectricDerivativeMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | srt_EnergyAxis=ava_GasDerivativeMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_DerivativeInstrumentRiskAxis=ava_FinancialMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_IncomeStatementLocationAxis=us-gaap_SalesMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |