XML 64 R45.htm IDEA: XBRL DOCUMENT
v3.8.0.1

Derivatives And Risk Management (Interest Rate Swap Agreements) (Details) - Interest Rate Swap [Member] $ in Thousands | 3 Months Ended | 12 Months Ended
--- | --- | ---
Mar. 31, 2018 USD ($) Caontracts | Dec. 31, 2017 USD ($) Caontracts
2018 |  |
Derivatives, Fair Value [Line Items] |  |
Number of Interest Rate Derivatives Held | Caontracts | 14 | 14
Derivative, Notional Amount | $ | $ 275,000 | $ 275,000
Derivative, Maturity Date | Dec. 31, 2018 | Dec. 31, 2018
2019 |  |
Derivatives, Fair Value [Line Items] |  |
Number of Interest Rate Derivatives Held | Caontracts | 6 | 6
Derivative, Notional Amount | $ | $ 70,000 | $ 70,000
Derivative, Maturity Date | Dec. 31, 2019 | Dec. 31, 2019
2020 |  |
Derivatives, Fair Value [Line Items] |  |
Number of Interest Rate Derivatives Held | Caontracts | 4 | 3
Derivative, Notional Amount | $ | $ 40,000 | $ 30,000
Derivative, Maturity Date | Dec. 31, 2020 | Dec. 31, 2020
2021 |  |
Derivatives, Fair Value [Line Items] |  |
Number of Interest Rate Derivatives Held | Caontracts | 1 | 1
Derivative, Notional Amount | $ | $ 15,000 | $ 15,000
Derivative, Maturity Date | Dec. 31, 2021 | Dec. 31, 2021
2022 |  |
Derivatives, Fair Value [Line Items] |  |
Number of Interest Rate Derivatives Held | Caontracts | 5 | 5
Derivative, Notional Amount | $ | $ 60,000 | $ 60,000
Derivative, Maturity Date | Dec. 31, 2022 | Dec. 31, 2022

X
- Definition Aggregate notional amount specified by the derivative(s). Expressed as an absolute value. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Regulation S-X (SX) -Number 210 -Article 12 -Section 13 -Sentence Column B + Details
Name: | invest_DerivativeNotionalAmount
Namespace Prefix: | invest_
Data Type: | xbrli:monetaryItemType
Balance Type: | na
Period Type: | instant

X
- Definition Date the derivative contract matures, in CCYY-MM-DD format. + References No definition available. + Details
Name: | us-gaap_DerivativeMaturityDates
Namespace Prefix: | us-gaap_
Data Type: | xbrli:dateItemType
Balance Type: | na
Period Type: | duration

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

X
- Definition Number of interest rate derivative instruments held by the entity at the reporting date. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 815 -SubTopic 10 -Section 50 -Paragraph 1B -URI http://asc.fasb.org/extlink&oid=84234895&loc=SL5580258-113959 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 815 -SubTopic 10 -Section 50 -Paragraph 1A -Subparagraph (d) -URI http://asc.fasb.org/extlink&oid=84234895&loc=SL5579245-113959 + Details
Name: | us-gaap_NumberOfInterestRateDerivativesHeld
Namespace Prefix: | us-gaap_
Data Type: | xbrli:integerItemType
Balance Type: | na
Period Type: | instant

X
- Details
Name: | ava_DerivativesCashSettlementDateAxis=ava_TwoThousandEighteenMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

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

X
- Details
Name: | ava_DerivativesCashSettlementDateAxis=ava_TwoThousandNineteenMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | ava_DerivativesCashSettlementDateAxis=ava_TwoThousandTwentyMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | ava_DerivativesCashSettlementDateAxis=ava_TwoThousandTwentyOneMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | ava_DerivativesCashSettlementDateAxis=ava_TwoThousandTwentyTwoMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |