XML 62 R38.htm IDEA: XBRL DOCUMENT
v3.19.3

Long- Term Debt to Affiliated Trust Long-Term Debt to Affiliated Trust (Tables) | 9 Months Ended
--- | ---
Sep. 30, 2019
Long-Term Debt to Affiliated Trust [Abstract] |
Schedule Of Distribution Rates Paid [Table Text Block] | The distribution rates paid were as follows during the nine months ended September 30, 2019 and the year ended December 31, 2018:
| September 30, |  | December 31,
| 2019 |  | 2018
Low distribution rate | 3.01 | % |  | 2.36 | %
High distribution rate | 3.40 | % |  | 3.61 | %
Distribution rate at the end of the period | 3.01 | % |  | 3.61 | %

X
- Definition Long-Term Debt to Affiliated Trust [Abstract] + References No definition available. + Details
Name: | ava_LongTermDebttoAffiliatedTrustAbstract
Namespace Prefix: | ava_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Definition Schedule Of Distribution Rates Paid [Table Text Block] + References No definition available. + Details
Name: | ava_ScheduleOfDistributionRatesPaidTableTextBlock
Namespace Prefix: | ava_
Data Type: | nonnum:textBlockItemType
Balance Type: | na
Period Type: | duration