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 in Net Income (Loss) Other Noncontrolling Interests, Redeemable						27
Noncontrolling Interest in Net Income (Loss) Other Noncontrolling Interests, Nonredeemable					733
Issuance of common stock		99,291
Equity compensation expense		1,461
Issuance of common stock, net of issuance costs		1,149
Equity transactions of consolidated subsidiaries		(88)
Other comprehensive loss	113		113
Net income attributable to Avista Corporation shareholders	42,341			42,341
Cash dividends paid (common stock)				(18,384)
Total equity	1,304,738
Other					2,371
Purchase of subsidiary noncontrolling interests						0
Valuation adjustments and other noncontrolling interests activity				(2,093)		3,005
Ending Balance at Mar. 31, 2013	1,283,976	891,759	(6,587)	398,804	20,762	7,970
Ending Balance (in shares) at Mar. 31, 2013		59,912,087
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 in Net Income (Loss) Other Noncontrolling Interests, Redeemable						24
Noncontrolling Interest in Net Income (Loss) Other Noncontrolling Interests, Nonredeemable					458
Issuance of common stock		84,388
Equity compensation expense		1,619
Issuance of common stock, net of issuance costs		638
Equity transactions of consolidated subsidiaries		(213)
Other comprehensive loss	894		894
Net income attributable to Avista Corporation shareholders	48,499			48,499
Cash dividends paid (common stock)				(19,217)
Total equity	1,351,113
Other					172
Purchase of subsidiary noncontrolling interests						(3)
Valuation adjustments and other noncontrolling interests activity				(4)		50
Ending Balance at Mar. 31, 2014	$ 1,330,482	$ 899,037	$ (4,925)	$ 436,370	$ 20,631	$ 15,960
Ending Balance (in shares) at Mar. 31, 2014	60,161,140	60,161,140