Consolidated Statements Of Income - USD ($) shares in Thousands, $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Operating Revenues:
Utility Revenues Excluding Alternative Revenue Programs	$ 1,323,524	$ 1,368,657	$ 1,442,980
Revenue from Alternative Revenue Programs	9,614	908	(19,594)
Total utility revenues	1,333,138	1,369,565	1,423,386
Non-utility revenues	12,484	27,328	22,543
Total operating revenues	1,345,622	1,396,893	1,445,929
Utility operating expenses:
Resource costs	439,817	494,736	524,566
Other operating expenses	345,212	318,274	310,143
Merger transaction costs	19,675	3,718	14,618
Depreciation and amortization	205,365	182,877	171,281
Taxes other than income taxes	105,652	107,295	106,752
Non-utility operating expenses:
Other operating expenses	18,883	28,081	25,650
Depreciation, Depletion and Amortization, Nonproduction	629	799	740
Total operating expenses	1,135,233	1,135,780	1,153,750
Income from operations	210,389	261,113	292,179
Interest expense	103,012	99,715	95,361
Interest expense to affiliated trusts	1,342	1,221	831
Capitalized Interest	(4,174)	(3,939)	(3,310)
Termination Fee Received from Canceled Business Acquisition	(103,000)	0	0
Other expense (income)-net	(14,928)	1,458	607
Income before income taxes	228,137	162,658	198,690
Income tax expense	31,374	26,060	82,758
Net income	196,763	136,598	115,932
Net loss (income) attributable to noncontrolling interests	216	(169)	(16)
Net income attributable to Avista Corp. shareholders	$ 196,979	$ 136,429	$ 115,916
Weighted-average common shares outstanding (thousands), basic	66,205	65,673	64,496
Weighted-average common shares outstanding (thousands), diluted	66,329	65,946	64,806
Earnings per common share attributable to Avista Corporation shareholders:
Earnings Per Share, Basic	$ 2.98	$ 2.08	$ 1.80
Earnings Per Share, Diluted	$ 2.97	$ 2.07	$ 1.79