XML 101 R76.htm IDEA: XBRL DOCUMENT
v3.20.2

Accumulated Other Comprehensive Loss - Schedule of Accumulated Other Comprehensive Loss, Net of Tax (Parenthetical) (Details) - USD ($) $ in Thousands | Sep. 30, 2020 | Dec. 31, 2019
--- | --- | ---
Accumulated Other Comprehensive Loss [Abstract] |  |
Accumulated other comprehensive income (loss), pension and other postretirement benefit plans net unamortized (gain) loss, tax | $ 2,556 | $ 2,727

X
- Definition Accumulated Other Comprehensive Income (Loss), Pension and Other Postretirement Benefit Plans Net Unamortized (Gain) Loss, Tax + References No definition available. + Details
Name: | ava_AccumulatedOtherComprehensiveIncomeLossPensionAndOtherPostretirementBenefitPlansNetUnamortizedGainLossTax
Namespace Prefix: | ava_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition Accumulated Other Comprehensive Loss [Abstract] + References No definition available. + Details
Name: | ava_AccumulatedOtherComprehensiveLossAbstract
Namespace Prefix: | ava_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration