Common Stock Common Stock (Dividends Declared) (Details) $ in Millions	Dec. 31, 2019 USD ($)
Dividend Restrictions [Line Items]
Amount Available For Dividend Distribution Without Affecting Covenants	$ 293.9
Avista Utilities [Member]
Dividend Restrictions [Line Items]
Regulatory Restrictions, Maximum Debt to Equity	35.00%

Amount Available For Dividend Distribution Without Affecting Covenants

No definition available.

Name:	ava_AmountAvailableForDividendDistributionWithoutAffectingCovenants
Namespace Prefix:	ava_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant