Commitments And Contingencies (Details) (USD $)	1 Months Ended	9 Months Ended
	May 31, 2004	Sep. 30, 2014 hydroelectric_plant employee gal
Number Of Bargaining Unit Employees Oregon		50
Amount of Regulatory Costs Not yet Approved		$ 1,300,000
Gallons of Diesel Spilled		10,000
Investigation review bid maximum (per MW)	250
Litigation Settlement, Amount		$ 15,000,000
Number of hydroelectric plants		6
Number of years, license issued		50 years
Avista Utilities [Member]
Percentage Of Employees, Collective Bargaining Agreement		45.00%
Majority Of Bargaining Unit Employees, Percentage		90.00%
Alaska Electric Light & Power [Member]
Percentage Of Employees, Collective Bargaining Agreement		54.00%