Consolidated Statements Of Income (USD $) In Thousands, except Per Share data, unless otherwise specified	12 Months Ended
	Dec. 31, 2012		Dec. 31, 2011		Dec. 31, 2010
Operating Revenues:
Utility revenues	$ 1,352,385		$ 1,441,522		$ 1,417,846
Ecova revenues	155,664		137,848		102,035
Other non-utility revenues	38,953		40,410		38,859
Total operating revenues	1,547,002		1,619,780		1,558,740
Utility operating expenses:
Resource costs	693,127		790,048		795,075
Other operating expenses	276,780		261,926		252,437
Depreciation and amortization	112,091		105,629		100,554
Taxes other than income taxes	83,409		83,347		73,382
Ecova operating expenses:
Other operating expenses	139,173		109,738		80,100
Depreciation and amortization	13,519		7,193		6,070
Other non-utility operating expenses:
Other operating expenses	38,041		33,117		30,386
Depreciation and amortization	792		778		1,002
Total operating expenses	1,356,932		1,391,776		1,339,006
Income from operations	190,070	[1]	228,004	[1]	219,734	[1]
Interest expense	76,894		73,876		75,789
Interest expense to affiliated trusts	541		332		635
Capitalized interest	(2,401)		(2,942)		(298)
Other income-net	(5,025)	[2]	(3,433)	[2]	(2,497)	[2]
Income before income taxes	120,061		160,171		146,105
Income tax expense	41,261		56,632		51,157
Net income	78,800		103,539		94,948
Comprehensive Income (Loss), Net of Tax, Attributable to Noncontrolling Interest	590		3,315		2,523
Net income attributable to Avista Corporation shareholders	$ 78,210		$ 100,224		$ 92,425
Weighted-average common shares outstanding (thousands), basic	59,028		57,872		55,595
Weighted-average common shares outstanding (thousands), diluted	59,201		58,092		55,824
Earnings per common share attributable to Avista Corporation shareholders:
Basic	$ 1.32		$ 1.73		$ 1.66
Diluted (usd per share)	$ 1.32		$ 1.72		$ 1.65
Dividends paid per common share	$ 1.16		$ 1.10		$ 1.00

[1] Includes an immaterial correction of an error related to the reclassification of certain operating expenses from other expense-net to utility and non-utility other operating expenses and utility taxes other than income taxes. This correction did not have an impact on net income or earnings per share. See Note 1 for further information regarding this reclassification.

[2] Includes an immaterial correction of an error related to the reclassification of certain operating expenses from other expense-net to utility and non-utility other operating expenses and utility taxes other than income taxes. This correction did not have an impact on net income or earnings per share. See further discussion of this reclassification below under "Immaterial Correction of an Error".