Derivatives And Risk Management (Energy Commodity Derivatives) (Details)	6 Months Ended
	Jun. 30, 2014 frequency
Sales [Member] | Physical [Member] | Electric Derivative [Member]
Energy Commodity Derivative Volumes [Line Items]
2014	465,000	[1]
2015	222,000	[1]
2016	287,000	[1]
2017	286,000	[1]
2018	286,000	[1]
Thereafter	158,000	[1]
Sales [Member] | Physical [Member] | Gas Derivative [Member]
Energy Commodity Derivative Volumes [Line Items]
2014	2,620,000	[1]
2015	1,490,000	[1]
2016	910,000	[1]
2017	0	[1]
2018	0	[1]
Thereafter	0	[1]
Sales [Member] | Financial [Member] | Electric Derivative [Member]
Energy Commodity Derivative Volumes [Line Items]
2014	1,768,000	[1]
2015	2,935,000	[1]
2016	1,634,000	[1]
2017	0	[1]
2018	0	[1]
Thereafter	0	[1]
Sales [Member] | Financial [Member] | Gas Derivative [Member]
Energy Commodity Derivative Volumes [Line Items]
2014	59,008,000	[1]
2015	68,710,000	[1]
2016	46,220,000	[1]
2017	0	[1]
2018	0	[1]
Thereafter	0	[1]
Purchase [Member] | Physical [Member] | Electric Derivative [Member]
Energy Commodity Derivative Volumes [Line Items]
2014	515,000	[1]
2015	508,000	[1]
2016	397,000	[1]
2017	397,000	[1]
2018	397,000	[1]
Thereafter	235,000	[1]
Purchase [Member] | Physical [Member] | Gas Derivative [Member]
Energy Commodity Derivative Volumes [Line Items]
2014	13,854,000	[1]
2015	7,113,000	[1]
2016	2,505,000	[1]
2017	675,000	[1]
2018	0	[1]
Thereafter	0	[1]
Purchase [Member] | Financial [Member] | Electric Derivative [Member]
Energy Commodity Derivative Volumes [Line Items]
2014	1,467,000	[1]
2015	1,546,000	[1]
2016	948,000	[1]
2017	0	[1]
2018	0	[1]
Thereafter	0	[1]
Purchase [Member] | Financial [Member] | Gas Derivative [Member]
Energy Commodity Derivative Volumes [Line Items]
2014	80,796,000	[1]
2015	103,025,000	[1]
2016	56,680,000	[1]
2017	0	[1]
2018	0	[1]
Thereafter	0	[1]

[1] Physical transactions represent commodity transactions where Avista Utilities will take delivery of either electricity or natural gas and financial transactions represent derivative instruments with no physical delivery, such as futures, swaps or options.