Consolidated Statements Of Equity And Redeemable Noncontrolling Interests (USD $) In Thousands, except Share data	Total	Common Stock [Member]	Accumulated Other Comprehensive Income (Loss) [Member]	Retained Earnings [Member]	Noncontrolling Interests [Member]	Redeemable Noncontrolling Interests [Member]
Beginning Balance at Dec. 31, 2012		$ 889,237	$ (6,700)	$ 376,940	$ 17,658	$ 4,938
Beginning Balance (in shares) at Dec. 31, 2012		59,812,796
Noncontrolling Interest, Decrease from Deconsolidation	0
Noncontrolling Interest in Net Income (Loss) Other Noncontrolling Interests, Redeemable						56
Noncontrolling Interest in Net Income (Loss) Other Noncontrolling Interests, Nonredeemable					777
Issuance of common stock		167,227
Equity compensation expense		2,968
Issuance of common stock, net of issuance costs		3,017
Equity transactions of consolidated subsidiaries		33
Other comprehensive loss	(936)		(936)
Net income attributable to Avista Corporation shareholders	67,998			67,998
Cash dividends paid (common stock)				(36,667)
Total equity	1,314,421
Other					2,172
Purchase of subsidiary noncontrolling interests						(325)
Valuation adjustments and other noncontrolling interests activity				(2,076)		3,148
Payments for Repurchase of Redeemable Noncontrolling Interest	0
Excess Tax Benefit from Share-based Compensation, Financing Activities	0
Ending Balance at Jun. 30, 2013	1,293,814	895,255	(7,636)	406,195	20,607	7,817
Ending Balance (in shares) at Jun. 30, 2013		59,980,023
Beginning Balance at Dec. 31, 2013	1,298,266	896,993	(5,819)	407,092	20,001	15,889
Beginning Balance (in shares) at Dec. 31, 2013	60,076,752	60,076,752
Noncontrolling Interest, Decrease from Deconsolidation	23,612
Noncontrolling Interest in Net Income (Loss) Other Noncontrolling Interests, Redeemable						(4)
Noncontrolling Interest in Net Income (Loss) Other Noncontrolling Interests, Nonredeemable					197
Issuance of common stock		143,347
Equity compensation expense		4,765
Issuance of common stock, net of issuance costs		1,980
Equity transactions of consolidated subsidiaries		(1,062)
Other comprehensive loss	1,809		1,809
Net income attributable to Avista Corporation shareholders	149,370			149,370
Cash dividends paid (common stock)				(38,327)
Total equity	1,409,545
Other					2,943
Purchase of subsidiary noncontrolling interests						(12)
Valuation adjustments and other noncontrolling interests activity				10,150		(15,873)
Payments for Repurchase of Redeemable Noncontrolling Interest	(20,871)
Excess Tax Benefit from Share-based Compensation, Financing Activities	3,936
Ending Balance at Jun. 30, 2014	$ 1,410,016	$ 885,741	$ (4,010)	$ 528,285	$ (471)	$ 0
Ending Balance (in shares) at Jun. 30, 2014	60,220,099	60,220,099