Consolidated Statements Of Income - USD ($) shares in Thousands, $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2016	Sep. 30, 2015
Operating Revenues:
Utility revenues	$ 296,989	$ 307,405	$ 1,022,670	$ 1,074,642
Other non-utility revenues	6,360	6,244	17,690	22,829
Total operating revenues	303,349	313,649	1,040,360	1,097,471
Utility operating expenses:
Resource costs	118,737	138,210	390,271	488,886
Other operating expenses	75,160	74,315	229,605	220,599
Depreciation and amortization	40,240	36,303	119,110	106,279
Taxes other than income taxes	22,669	22,269	74,669	75,424
Other non-utility operating expenses:
Other operating expenses	6,756	6,462	18,862	22,924
Depreciation and amortization	193	178	573	512
Total operating expenses	263,755	277,737	833,090	914,624
Income from operations	39,594	35,912	207,270	182,847
Interest expense	21,632	19,951	64,223	59,719
Interest expense to affiliated trusts	164	120	456	347
Capitalized interest	(507)	(905)	(2,258)	(2,701)
Other income-net	(1,562)	(2,123)	(7,025)	(6,190)
Income before income taxes	19,867	18,869	151,874	131,672
Income tax expense	7,606	6,115	54,661	47,378
Net income from continuing operations	12,261	12,754	97,213	84,294
Net income from discontinued operations (Note 3)	0	289	0	485
Net income	12,261	13,043	97,213	84,779
Net income attributable to noncontrolling interests	(27)	(32)	(76)	(73)
Net income attributable to Avista Corporation shareholders	12,234	13,011	97,137	84,706
Net income from continuing operations attributable to Avista Corp. shareholders	12,234	12,722	97,137	84,221
Net income from discontinued operations attributable to Avista Corp. shareholders	$ 0	$ 289	$ 0	$ 485
Weighted-average common shares outstanding (thousands), basic	63,857	62,299	63,282	62,299
Weighted-average common shares outstanding (thousands), diluted	64,325	62,688	63,687	62,691
Earnings Per Share, Basic [Abstract]
Earnings per common share from continuing operations	$ 0.19	$ 0.21	$ 1.53	$ 1.35
Earnings per common share from discontinued operations	0.00	0.00	0.00	0.01
Total earnings per common share attributable to Avista Corp. shareholders, basic	0.19	0.21	1.53	1.36
Earnings Per Share, Diluted [Abstract]
Earnings per common share from continuing operations	0.19	0.21	1.53	1.34
Earnings per common share from discontinued operations	0.00	0.00	0.00	0.01
Total earnings per common share attributable to Avista Corp. shareholders, diluted	0.19	0.21	1.53	1.35
Common Stock, Dividends, Per Share, Cash Paid	$ 0.3425	$ 0.3300	$ 1.0275	$ 0.9900