Consolidated Statements Of Income (USD $) In Thousands, except Per Share data, unless otherwise specified	3 Months Ended				6 Months Ended
	Jun. 30, 2013		Jun. 30, 2012		Jun. 30, 2013		Jun. 30, 2012
Operating Revenues:
Utility revenues	$ 297,719		$ 293,315		$ 728,846		$ 698,775
Ecova revenues	44,560		40,080		86,967		77,090
Other non-utility revenues	9,769		10,190		19,141		19,977
Total operating revenues	352,048		343,585		834,954		795,842
Utility operating expenses:
Resource costs	126,511		135,992		356,141		347,004
Other operating expenses	65,784		64,981		131,228		130,303
Depreciation and amortization	29,025		27,754		56,960		55,072
Taxes other than income taxes	21,608		20,435		47,425		45,601
Ecova operating expenses:
Other operating expenses	37,716		34,750		73,706		70,524
Depreciation and amortization	4,072		3,359		7,565		6,195
Other non-utility operating expenses:
Other operating expenses	9,415		10,082		18,760		18,349
Depreciation and amortization	175		212		365		380
Total operating expenses	294,306		297,565		692,150		673,428
Income from operations	57,742	[1]	46,020	[1]	142,804	[1]	122,414	[1]
Interest expense	19,861		19,188		39,553		38,325
Interest expense to affiliated trusts	117		137		235		277
Capitalized interest	(942)		(596)		(1,882)		(1,121)
Other income-net	(2,436)	[2]	(1,601)	[2]	(4,581)	[2]	(3,310)	[2]
Income before income taxes	41,142		28,892		109,479		88,243
Income tax expense	15,412		10,360		40,648		31,498
Net income	25,730		18,532		68,831		56,745
Net income attributable to noncontrolling interests	(73)		(354)		(833)		(179)
Net income attributable to Avista Corporation shareholders	$ 25,657		$ 18,178		$ 67,998		$ 56,566
Weighted-average common shares outstanding (thousands), basic	59,937		58,702		59,926		58,642
Weighted-average common shares outstanding (thousands), diluted	59,962		58,924		59,954		58,937
Earnings per common share attributable to Avista Corporation shareholders:
Basic (usd per share)	$ 0.43		$ 0.31		$ 1.13		$ 0.96
Diluted (usd per share)	$ 0.43		$ 0.31		$ 1.13		$ 0.96
Dividends paid per common share	$ 0.305		$ 0.29		$ 0.61		$ 0.58

[1] Includes a correction of an immaterial 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] The 2012 amount includes a correction of an immaterial 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 "Correction of an Immaterial Error."