Information by Business Segments - Schedule of Business Segments (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2022	Sep. 30, 2021	Sep. 30, 2022	Sep. 30, 2021	Dec. 31, 2021
Segment Reporting Information [Line Items]
Operating revenues	$ 359,446	$ 296,007	$ 1,200,058	$ 1,007,132
Resource costs	147,784	102,133	492,049	327,390
Other operating expenses	102,742	86,468	305,617	270,419
Depreciation and amortization	63,516	57,752	188,961	169,239
Income (loss) from operations	19,402	24,214	126,654	157,861
Interest expense	29,835	26,649	86,714	79,299
Income taxes	157	(5,432)	(11,678)	9,130
Net (loss) income	(5,798)	14,366	77,220	96,457
Capital expenditures	120,663	109,354	332,065	323,746
Total Assets	7,055,799		7,055,799		$ 6,853,583
Avista Utilities [Member]
Segment Reporting Information [Line Items]
Operating revenues	349,655	286,752	1,167,042	974,172
Alaska Electric Light & Power [Member]
Segment Reporting Information [Line Items]
Operating revenues	9,637	9,147	32,597	32,515
Operating Segments [Member] | Utility Revenue [Member]
Segment Reporting Information [Line Items]
Operating revenues	359,292	295,899	1,199,639	1,006,687
Resource costs	147,784	102,133	492,049	327,390
Other operating expenses	101,701	85,625	300,710	267,233
Depreciation and amortization	63,484	57,722	188,867	169,009
Income (loss) from operations	20,321	24,979	131,236	160,832
Interest expense	29,703	26,538	86,327	78,994
Income taxes	218	(6,353)	(13,658)	6,751
Net (loss) income	(5,759)	9,127	69,533	85,677
Capital expenditures	120,663	108,981	331,309	322,808
Total Assets	6,915,510		6,915,510		6,723,666
Operating Segments [Member] | Avista Utilities [Member] | Utility Revenue [Member]
Segment Reporting Information [Line Items]
Operating revenues	349,655	286,752	1,167,042	974,172
Resource costs	146,384	101,109	489,029	324,464
Other operating expenses	98,062	82,006	289,828	257,333
Depreciation and amortization	60,780	55,039	180,765	161,332
Income (loss) from operations	18,660	23,416	121,476	149,670
Interest expense	28,214	25,015	81,864	74,423
Income taxes	197	(6,371)	(14,728)	4,932
Net (loss) income	(5,987)	9,086	65,241	80,861
Capital expenditures	116,809	107,519	324,123	318,354
Total Assets	6,648,603		6,648,603		6,458,244
Operating Segments [Member] | Alaska Electric Light & Power [Member] | Utility Revenue [Member]
Segment Reporting Information [Line Items]
Operating revenues	9,637	9,147	32,597	32,515
Resource costs	1,400	1,024	3,020	2,926
Other operating expenses	3,639	3,619	10,882	9,900
Depreciation and amortization	2,704	2,683	8,102	7,677
Income (loss) from operations	1,661	1,563	9,760	11,162
Interest expense	1,489	1,523	4,463	4,571
Income taxes	21	18	1,070	1,819
Net (loss) income	228	41	4,292	4,816
Capital expenditures	3,854	1,462	7,186	4,454
Total Assets	266,907		266,907		265,422
Other [Member] | Non-Utility Revenue [Member]
Segment Reporting Information [Line Items]
Operating revenues	154	108	419	445
Resource costs	0	0	0	0
Other operating expenses	1,041	843	4,907	3,186
Depreciation and amortization	32	30	94	230
Income (loss) from operations	(919)	(765)	(4,582)	(2,971)
Interest expense	243	132	508	392
Income taxes	(61)	921	1,980	2,379
Net (loss) income	(39)	5,239	7,687	10,780
Capital expenditures	0	373	756	938
Total Assets	149,077		149,077		132,158
Intersegment Eliminations [Member]
Segment Reporting Information [Line Items]
Operating revenues	0	0	0	0
Resource costs	0	0	0	0
Other operating expenses	0	0	0	0
Depreciation and amortization	0	0	0	0
Income (loss) from operations	0	0	0	0
Interest expense	(111)	(21)	(121)	(87)
Income taxes	0	0	0	0
Net (loss) income	0	0	0	0
Capital expenditures	0	$ 0	0	$ 0
Total Assets	$ (8,788)		$ (8,788)		$ (2,241)