Accounting For Income Taxes (Narrative) (Details) - USD ($) $ in Millions	12 Months Ended			24 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2017
Components of Income Tax Expense (Benefit) [Line Items]
Federal statutory tax rate	21.00%	35.00%	35.00%	35.00%
Avista Utilities [Member]
Components of Income Tax Expense (Benefit) [Line Items]
Tax Cuts and Jobs Act Period to Return Plant Related Excess Deferred Income Taxes	36 years
Alaska Electric Light & Power [Member]
Components of Income Tax Expense (Benefit) [Line Items]
Tax Cuts and Jobs Act Period to Return Plant Related Excess Deferred Income Taxes	40 years
Excess Deferred Income Taxes Plant Related [Member] [Member]
Components of Income Tax Expense (Benefit) [Line Items]
Regulatory Liability For Excess Deferred Income Taxes	$ 436.7	$ 442.3		$ 442.3
Excess Deferred Income Taxes Non-plant Related [Member]
Components of Income Tax Expense (Benefit) [Line Items]
Regulatory Liability For Excess Deferred Income Taxes	$ 18.5