Revenue Revenue Utility Related Taxes (Details) - USD ($) $ in Thousands	3 Months Ended
Mar. 31, 2020	Mar. 31, 2019
Revenue from Contract with Customer [Abstract]
Public Utility Operating Expenses Excise Taxes Collected	$ 18,700	$ 19,089

Public Utility Operating Expenses Excise Taxes Collected and Reported Gross in Revenues and Operating Expenses

No definition available.

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Namespace Prefix:	ava_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration