Summary Of Significant Accounting Policies (Effective AFUDC Rate) (Details)	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Avista Utilities [Member]
Effective Rate On Allowance For Funds Used During Construction [Line Items]
Effective AFUDC rate	7.32%	7.64%	7.64%
Alaska Electric Light & Power [Member]
Effective Rate On Allowance For Funds Used During Construction [Line Items]
Effective AFUDC rate	9.31%	10.37%