Derivatives And Risk Management (Derivative Instruments Summary) (Details) (USD $)	Jun. 30, 2014		Dec. 31, 2013
Derivatives, Fair Value [Line Items]
Gross Asset	$ 91,163,000		$ 89,132,000
Gross Liability	(105,781,000)		(89,675,000)
Collateral Netting	10,091,000		8,732,000
Net Asset (Liability) in Balance Sheet	(4,527,000)		8,189,000
Other Current Liabilities [Member] | Foreign Exchange Contract [Member]
Derivatives, Fair Value [Line Items]
Gross Asset	136,000		7,000
Gross Liability	(1,000)		(6,000)
Collateral Netting	0		0
Net Asset (Liability) in Balance Sheet	135,000		1,000
Other Current Liabilities [Member] | Interest Rate Contracts [Member]
Derivatives, Fair Value [Line Items]
Gross Asset	8,211,000		13,968,000
Gross Liability	0		0
Collateral Netting	0		0
Net Asset (Liability) in Balance Sheet	8,211,000		13,968,000
Other Property and Investments-Net [Member] | Interest Rate Contracts [Member]
Derivatives, Fair Value [Line Items]
Gross Asset	5,809,000		19,575,000
Gross Liability	(2,269,000)		0
Collateral Netting	0		0
Net Asset (Liability) in Balance Sheet	3,540,000		19,575,000
Current Utility Energy Commodity Derivative Assets [Member] | Commodity Contracts [Member]
Derivatives, Fair Value [Line Items]
Gross Asset	50,416,000	[1]	7,416,000	[1]
Gross Liability	(39,547,000)	[1]	(4,394,000)	[1]
Collateral Netting	0	[1]	0	[1]
Net Asset (Liability) in Balance Sheet	10,869,000	[1]	3,022,000	[1]
Non-Current Utility Energy Commodity Derivative Assets [Member] | Commodity Contracts [Member]
Derivatives, Fair Value [Line Items]
Gross Asset	367,000	[1]	7,610,000	[1]
Gross Liability	(92,000)	[1]	(6,756,000)	[1]
Collateral Netting	0	[1]	0	[1]
Net Asset (Liability) in Balance Sheet	275,000	[1]	854,000	[1]
Current Utility Energy Commodity Derivative Liabilities [Member] | Commodity Contracts [Member]
Derivatives, Fair Value [Line Items]
Gross Asset	2,232,000	[1]	23,455,000	[1]
Gross Liability	(5,610,000)	[1]	(37,306,000)	[1]
Collateral Netting	0	[1]	2,976,000	[1]
Net Asset (Liability) in Balance Sheet	(3,378,000)	[1]	(10,875,000)	[1]
Other Noncurrent Liabilities [Member] | Interest Rate Contracts [Member]
Derivatives, Fair Value [Line Items]
Gross Asset	1,617,000
Gross Liability	(22,308,000)
Collateral Netting	7,040,000
Net Asset (Liability) in Balance Sheet	(13,651,000)
Other Noncurrent Liabilities [Member] | Commodity Contracts [Member]
Derivatives, Fair Value [Line Items]
Gross Asset	22,375,000	[1]	17,101,000	[1]
Gross Liability	(35,954,000)	[1]	(41,213,000)	[1]
Collateral Netting	3,051,000	[1]	5,756,000	[1]
Net Asset (Liability) in Balance Sheet	$ (10,528,000)	[1]	$ (18,356,000)	[1]

[1] Avista Corp. had a master netting agreement that governed the transactions of multiple affiliated legal entities under this single master netting agreement. This master netting agreement allowed for cross-commodity netting (i.e. netting physical power, physical natural gas, and financial transactions) and cross-affiliate netting for the parties to the agreement. Avista Corp. performed cross-commodity netting for each legal entity that is a party to the master netting agreement for presentation in the Condensed Consolidated Balance Sheets; however, Avista Corp. did not perform cross-affiliate netting because the Company believed that cross-affiliate netting may not be enforceable. Therefore, the requirements for cross-affiliate netting under ASC 210-20-45 were not applicable for Avista Corp. As of December 31, 2013, all derivatives for each affiliated entity under this master netting agreement were in a net liability position. As such, there was no additional netting which required disclosure for that period. In May 2014, this master netting agreement was terminated and each affiliated legal entity is now under their own separate agreement. As of June 30, 2014, the Company no longer has any agreements where cross-affiliate netting is allowed under the agreement, but not performed by the Company.