XML 100 R82.htm IDEA: XBRL DOCUMENT
v3.19.1

Termination of Proposed Acquisition by Hydro One Termination of Proposed Acquisition by Hydro One (Details) - USD ($) $ / shares in Units, $ in Thousands |  | 3 Months Ended |
--- | --- | --- | ---
Jan. 24, 2019 | Mar. 31, 2019 | Mar. 31, 2018 | Jul. 19, 2017
Business Acquisition [Line Items] |  |  |  |
Merger termination fee |  | $ 103,000 | $ 0 |
Merger transaction costs |  | $ 19,664 | $ 672 |
Hydro One [Member] |  |  |  |
Business Acquisition [Line Items] |  |  |  |
Business Acquisition, Share Price |  |  |  | $ 53
Merger termination fee | $ 103,000 |  |  |

X
- Definition Termination Fee Received from Canceled Business Acquisition + References No definition available. + Details
Name: | ava_TerminationFeeReceivedfromCanceledBusinessAcquisition
Namespace Prefix: | ava_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
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_BusinessAcquisitionLineItems
Namespace Prefix: | us-gaap_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Definition Price of a single share of a number of saleable stocks paid or offered to be paid in a business combination. + References No definition available. + Details
Name: | us-gaap_BusinessAcquisitionSharePrice
Namespace Prefix: | us-gaap_
Data Type: | num:perShareItemType
Balance Type: | na
Period Type: | instant

X
- Definition This element represents acquisition-related costs incurred to effect a business combination which costs have been expensed during the period. Such costs include finder's fees; advisory, legal, accounting, valuation, and other professional or consulting fees; general administrative costs, including the costs of maintaining an internal acquisitions department; and may include costs of registering and issuing debt and equity securities. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 805 -SubTopic 10 -Section 25 -Paragraph 23 -URI http://asc.fasb.org/extlink&oid=84229725&loc=d3e1043-128460 + Details
Name: | us-gaap_BusinessCombinationAcquisitionRelatedCosts
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Details
Name: | us-gaap_BusinessAcquisitionAxis=ava_HydroOneMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |