Information by Business Segments - Schedule of Business Segments (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2022	Jun. 30, 2021	Jun. 30, 2022	Jun. 30, 2021	Dec. 31, 2021
Segment Reporting Information [Line Items]
Operating revenues	$ 378,566	$ 298,255	$ 840,612	$ 711,125
Resource costs	157,397	90,678	344,265	225,257
Other operating expenses	107,392	95,212	202,875	183,951
Depreciation and amortization	62,836	56,139	125,445	111,487
Income (loss) from operations	24,283	31,752	107,252	133,647
Interest expense	28,695	26,237	56,879	52,650
Income taxes	(999)	2,398	(11,835)	14,562
Net income (loss)	11,453	14,074	83,018	82,091
Capital expenditures	115,001	117,161	211,402	214,392
Total Assets	6,937,714		6,937,714		$ 6,853,583
Avista Utilities [Member]
Segment Reporting Information [Line Items]
Operating revenues	368,515	287,560	817,387	687,420
Alaska Electric Light & Power [Member]
Segment Reporting Information [Line Items]
Operating revenues	9,906	10,547	22,960	23,368
Operating Segments [Member] | Utility Revenue [Member]
Segment Reporting Information [Line Items]
Operating revenues	378,421	298,107	840,347	710,788
Resource costs	157,397	90,678	344,265	225,257
Other operating expenses	104,482	94,053	199,009	181,608
Depreciation and amortization	62,806	56,066	125,383	111,287
Income (loss) from operations	27,078	32,836	110,915	135,853
Interest expense	28,565	26,131	56,624	52,456
Income taxes	(2,776)	1,053	(13,876)	13,104
Net income (loss)	4,721	9,016	75,292	76,550
Capital expenditures	114,659	116,624	210,646	213,827
Total Assets	6,797,893		6,797,893		6,723,666
Operating Segments [Member] | Avista Utilities [Member] | Utility Revenue [Member]
Segment Reporting Information [Line Items]
Operating revenues	368,515	287,560	817,387	687,420
Resource costs	156,221	89,515	342,645	223,355
Other operating expenses	100,782	90,728	191,766	175,327
Depreciation and amortization	60,106	53,569	119,985	106,293
Income (loss) from operations	25,037	29,561	102,816	126,254
Interest expense	27,078	24,608	53,650	49,408
Income taxes	(2,565)	585	(14,925)	11,303
Net income (loss)	3,950	7,717	71,228	71,775
Capital expenditures	111,850	114,441	207,314	210,835
Total Assets	6,528,546		6,528,546		6,458,244
Operating Segments [Member] | Alaska Electric Light & Power [Member] | Utility Revenue [Member]
Segment Reporting Information [Line Items]
Operating revenues	9,906	10,547	22,960	23,368
Resource costs	1,176	1,163	1,620	1,902
Other operating expenses	3,700	3,325	7,243	6,281
Depreciation and amortization	2,700	2,497	5,398	4,994
Income (loss) from operations	2,041	3,275	8,099	9,599
Interest expense	1,487	1,523	2,974	3,048
Income taxes	(211)	468	1,049	1,801
Net income (loss)	771	1,299	4,064	4,775
Capital expenditures	2,809	2,183	3,332	2,992
Total Assets	269,347		269,347		265,422
Other [Member] | Non-Utility Revenue [Member]
Segment Reporting Information [Line Items]
Operating revenues	145	148	265	337
Resource costs	0	0	0	0
Other operating expenses	2,910	1,159	3,866	2,343
Depreciation and amortization	30	73	62	200
Income (loss) from operations	(2,795)	(1,084)	(3,663)	(2,206)
Interest expense	137	131	265	260
Income taxes	1,777	1,345	2,041	1,458
Net income (loss)	6,732	5,058	7,726	5,541
Capital expenditures	342	537	756	565
Total Assets	148,097		148,097		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	(7)	(25)	(10)	(66)
Income taxes	0	0	0	0
Net income (loss)	0	0	0	0
Capital expenditures	0	$ 0	0	$ 0
Total Assets	$ (8,276)		$ (8,276)		$ (2,241)