XML 56 R37.htm IDEA: XBRL DOCUMENT
v3.8.0.1

New Accounting Standards New Accounting Standards (Details) - USD ($) $ in Thousands | 3 Months Ended
--- | ---
Mar. 31, 2018 | Mar. 31, 2017
AOCI Attributable to Parent [Member] |  |
New Accounting Pronouncements or Change in Accounting Principle [Line Items] |  |
Reclassification of excess income tax benefits | $ (1,742) | $ 0
Restatement Adjustment [Member] |  |
New Accounting Pronouncements or Change in Accounting Principle [Line Items] |  |
Defined Benefit Plan, Net Periodic Benefit Cost (Credit) |  | $ 2,000

X
- Definition Reclassification from AOCI to Retained Earnings -ASU 2018-02 was issued February 2018, which allows stranded tax effects associated with the enactment of the Tax Cuts and Jobs Act to be reclassified from AOCI to Retained Earnings. + References No definition available. + Details
Name: | ava_ReclassificationfromAOCItoRetainedEarnings
Namespace Prefix: | ava_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

X
- Definition Amount of net periodic benefit cost (credit) for defined benefit plan. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 715 -SubTopic 20 -Section 50 -Paragraph 1 -Subparagraph (h) -URI http://asc.fasb.org/extlink&oid=82843861&loc=d3e1928-114920 + Details
Name: | us-gaap_DefinedBenefitPlanNetPeriodicBenefitCost
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
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_NewAccountingPronouncementsOrChangeInAccountingPrincipleLineItems
Namespace Prefix: | us-gaap_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Details
Name: | us-gaap_StatementEquityComponentsAxis=us-gaap_AccumulatedOtherComprehensiveIncomeMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_StatementScenarioAxis=us-gaap_RestatementAdjustmentMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |