Derivatives And Risk Management (Energy Commodity Derivatives) (Details)	3 Months Ended
	Mar. 31, 2014 frequency
Sales [Member] | Physical [Member] | Electric Derivative [Member]
Energy Commodity Derivative Volumes [Line Items]
2014	688,000	[1]
2015	222,000	[1]
2016	256,000	[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	3,021,000	[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	2,522,000	[1]
2015	2,566,000	[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	87,043,000	[1]
2015	58,210,000	[1]
2016	41,490,000	[1]
2017	0	[1]
2018	0	[1]
Thereafter	0	[1]
Purchase [Member] | Physical [Member] | Electric Derivative [Member]
Energy Commodity Derivative Volumes [Line Items]
2014	725,000	[1]
2015	559,000	[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	18,282,000	[1]
2015	4,973,000	[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	1,768,000	[1]
2015	1,461,000	[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	110,762,000	[1]
2015	82,825,000	[1]
2016	51,950,000	[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.