XML 90 R64.htm IDEA: XBRL DOCUMENT
v3.10.0.1

Fair Value (Quantitative Information) (Details) $ / shares in Units, $ in Thousands | 6 Months Ended |
--- | --- | ---
Jun. 30, 2018 USD ($) $ / MWH MMBTU MWh $ / shares $ / MmBtu | Dec. 31, 2017 USD ($)
Power Exchange Agreements [Member] | Surrogate Facility Pricing [Member] |  |
Fair Value Inputs, Assets, Quantitative Information [Line Items] |  |
Transaction/Delivery Volumes | MWh | 292,145 |
Average operation and maintenance charges | $ / MWH | 45.61 |
Minimum [Member] | Power Exchange Agreements [Member] | Surrogate Facility Pricing [Member] |  |
Fair Value Inputs, Assets, Quantitative Information [Line Items] |  |
Fair Value Assumptions Operation And Maintenance Charges | $ / MWH | 40.05 |
Minimum [Member] | Power Option Agreement [Member] | Black Scholes Merton [Member] |  |
Fair Value Inputs, Assets, Quantitative Information [Line Items] |  |
Transaction/Delivery Volumes | MWh | 94,221 |
Maximum [Member] | Power Exchange Agreements [Member] | Surrogate Facility Pricing [Member] |  |
Fair Value Inputs, Assets, Quantitative Information [Line Items] |  |
Fair Value Assumptions Operation And Maintenance Charges | $ / MWH | 52.59 |
Maximum [Member] | Power Option Agreement [Member] | Black Scholes Merton [Member] |  |
Fair Value Inputs, Assets, Quantitative Information [Line Items] |  |
Transaction/Delivery Volumes | MWh | 96,907 |
Fair Value, Measurements, Recurring [Member] | Power Exchange Agreements [Member] |  |
Fair Value Inputs, Assets, Quantitative Information [Line Items] |  |
Derivative Liability | $ | $ (6,345) | $ (13,245)
Fair Value, Measurements, Recurring [Member] | Power Option Agreement [Member] |  |
Fair Value Inputs, Assets, Quantitative Information [Line Items] |  |
Derivative Liability | $ | (5) | (19)
Fair Value, Measurements, Recurring [Member] | Natural Gas Exchange Agreements [Member] |  |
Fair Value Inputs, Assets, Quantitative Information [Line Items] |  |
Derivative Liability | $ | $ (3,480) | $ (3,164)
Sales [Member] | Minimum [Member] | Natural Gas Exchange Agreements [Member] | Internally Derived Weighted Average Cost Of Gas [Member] |  |
Fair Value Inputs, Assets, Quantitative Information [Line Items] |  |
Derivative, Forward Price | $ / MmBtu | 1.34 |
Transaction/Delivery Volumes | MMBTU | 60,000 |
Sales [Member] | Maximum [Member] | Natural Gas Exchange Agreements [Member] | Internally Derived Weighted Average Cost Of Gas [Member] |  |
Fair Value Inputs, Assets, Quantitative Information [Line Items] |  |
Derivative, Forward Price | $ / MmBtu | 3.01 |
Transaction/Delivery Volumes | MMBTU | 310,000 |
Purchase [Member] | Minimum [Member] | Natural Gas Exchange Agreements [Member] | Internally Derived Weighted Average Cost Of Gas [Member] |  |
Fair Value Inputs, Assets, Quantitative Information [Line Items] |  |
Derivative, Forward Price | $ / MmBtu | 1.28 |
Transaction/Delivery Volumes | MMBTU | 115,000 |
Purchase [Member] | Maximum [Member] | Natural Gas Exchange Agreements [Member] | Internally Derived Weighted Average Cost Of Gas [Member] |  |
Fair Value Inputs, Assets, Quantitative Information [Line Items] |  |
Derivative, Forward Price | $ / MmBtu | 1.67 |
Transaction/Delivery Volumes | MMBTU | 310,000 |
2019 | Minimum [Member] | Power Option Agreement [Member] | Black Scholes Merton [Member] |  |
Fair Value Inputs, Assets, Quantitative Information [Line Items] |  |
Fair Value Assumptions, Exercise Price | $ / shares | $ 36.20 |
2019 | Maximum [Member] | Power Option Agreement [Member] | Black Scholes Merton [Member] |  |
Fair Value Inputs, Assets, Quantitative Information [Line Items] |  |
Fair Value Assumptions, Exercise Price | $ / shares | $ 41.55 |

X
- Definition Fair Value Assumptions, Average Operation And Maintenance Charges + References No definition available. + Details
Name: | ava_FairValueAssumptionsAverageOperationAndMaintenanceCharges
Namespace Prefix: | ava_
Data Type: | xbrli:decimalItemType
Balance Type: | na
Period Type: | instant

X
- Definition Fair Value Assumptions, Operation And Maintenance Charges + References No definition available. + Details
Name: | ava_FairValueAssumptionsOperationAndMaintenanceCharges
Namespace Prefix: | ava_
Data Type: | xbrli:decimalItemType
Balance Type: | na
Period Type: | instant

X
- Definition The forward price on the price risk forward or futures contract, such as a gas futures contract. + References No definition available. + Details
Name: | us-gaap_DerivativeForwardPrice
Namespace Prefix: | us-gaap_
Data Type: | us-types:perUnitItemType
Balance Type: | na
Period Type: | instant

X
- Definition Fair value, after the effects of master netting arrangements, of a financial liability or contract with one or more underlyings, notional amount or payment provision or both, and the contract can be net settled by means outside the contract or delivery of an asset. Includes liabilities not subject to a master netting arrangement and not elected to be offset. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 210 -SubTopic 20 -Section 55 -Paragraph 10 -URI http://asc.fasb.org/extlink&oid=82849420&loc=SL20226008-175313 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 825 -SubTopic 10 -Section 50 -Paragraph 15 -URI http://asc.fasb.org/extlink&oid=77997519&loc=d3e13495-108611 Reference 3: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 210 -SubTopic 20 -Section 50 -Paragraph 3 -Subparagraph (c) -URI http://asc.fasb.org/extlink&oid=51824906&loc=SL20225862-175312 Reference 4: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 825 -SubTopic 10 -Section 50 -Paragraph 10 -Subparagraph (a) -URI http://asc.fasb.org/extlink&oid=77997519&loc=d3e13433-108611 Reference 5: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 815 -SubTopic 10 -Section 45 -Paragraph 6 -URI http://asc.fasb.org/extlink&oid=6945355&loc=d3e41271-113958 Reference 6: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 815 -SubTopic 10 -Section 45 -Paragraph 5 -URI http://asc.fasb.org/extlink&oid=6945355&loc=d3e41228-113958 + Details
Name: | us-gaap_DerivativeLiabilities
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- Definition Nominal energy measure used to calculate payments on a derivative instrument. + References No definition available. + Details
Name: | us-gaap_DerivativeNonmonetaryNotionalAmountEnergyMeasure
Namespace Prefix: | us-gaap_
Data Type: | num:energyItemType
Balance Type: | na
Period Type: | duration

X
- Definition Agreed upon price for the exchange of the underlying asset. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 820 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (bbb) -URI http://asc.fasb.org/extlink&oid=66048111&loc=d3e19207-110258 + Details
Name: | us-gaap_FairValueAssumptionsExercisePrice
Namespace Prefix: | us-gaap_
Data Type: | num:perShareItemType
Balance Type: | na
Period Type: | instant

X
- 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_FairValueInputsAssetsQuantitativeInformationLineItems
Namespace Prefix: | us-gaap_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

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

X
- Details
Name: | us-gaap_ValuationTechniqueAxis=ava_SurrogateFacilityPricingMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_RangeAxis=us-gaap_MinimumMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

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

X
- Details
Name: | us-gaap_ValuationTechniqueAxis=ava_BlackScholesMertonMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_RangeAxis=us-gaap_MaximumMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_FairValueByMeasurementFrequencyAxis=us-gaap_FairValueMeasurementsRecurringMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_DerivativeInstrumentRiskAxis=ava_NaturalGasExchangeAgreementsMember
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: |

X
- Details
Name: | us-gaap_ValuationTechniqueAxis=ava_InternallyDerivedWeightedAverageCostOfGasMember
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: | ava_FairValueAssumptionDateAxis=ava_TwoThousandNineteenMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |