Consolidated Statements Of Income - USD ($) shares in Thousands, $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Operating Revenues:
Utility Revenues Excluding Alternative Revenue Programs	$ 1,368,657	$ 1,442,980	$ 1,389,256
Revenue from Alternative Revenue Programs	908	(19,594)	29,658
Total utility revenues	1,369,565	1,423,386	1,418,914
Non-utility revenues	27,328	22,543	23,569
Total operating revenues	1,396,893	1,445,929	1,442,483
Utility operating expenses:
Resource costs	494,736	524,566	551,366
Other operating expenses	318,274	310,143	305,737
Acquisition costs	3,718	14,618	0
Depreciation and amortization	182,877	171,281	160,514
Taxes other than income taxes	107,295	106,752	98,735
Non-utility operating expenses:
Other operating expenses	28,081	25,650	25,501
Depreciation, Depletion and Amortization, Nonproduction	799	740	769
Total operating expenses	1,135,780	1,153,750	1,142,622
Income from operations	261,113	292,179	299,861
Interest expense	99,715	95,361	86,496
Interest expense to affiliated trusts	1,221	831	634
Capitalized Interest	(3,939)	(3,310)	(2,651)
Other expense (income)-net	1,458	607	(20)
Income before income taxes	162,658	198,690	215,402
Income tax expense	26,060	82,758	78,086
Net income	136,598	115,932	137,316
Net income attributable to noncontrolling interests	(169)	(16)	(88)
Net income attributable to Avista Corp. shareholders	$ 136,429	$ 115,916	$ 137,228
Weighted-average common shares outstanding (thousands), basic	65,673	64,496	63,508
Weighted-average common shares outstanding (thousands), diluted	65,946	64,806	63,920
Earnings per common share attributable to Avista Corporation shareholders:
Earnings Per Share, Basic	$ 2.08	$ 1.80	$ 2.16
Earnings Per Share, Diluted	$ 2.07	$ 1.79	$ 2.15