Information by Business Segments - Schedule of Business Segments (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2023	Jun. 30, 2022	Jun. 30, 2023	Jun. 30, 2022	Dec. 31, 2022
Segment Reporting Information [Line Items]
Operating revenues	$ 379,937	$ 378,566	$ 854,568	$ 840,612
Resource costs	141,244	157,397	334,172	344,265
Other operating expenses	103,820	107,392	209,809	202,875
Depreciation and amortization	66,148	62,836	131,367	125,445
Income (loss) from operations	43,808	24,283	120,409	107,252
Interest expense	35,626	28,695	71,281	56,879
Income taxes	(5,810)	(999)	(12,438)	(11,835)
Net income (loss)	17,484	11,453	72,329	83,018
Capital expenditures	126,256	115,001	226,749	211,402
Total Assets	7,371,315		7,371,315		$ 7,417,350
Avista Utilities [Member]
Segment Reporting Information [Line Items]
Operating revenues	368,604	368,515	828,746	817,387
Alaska Electric Light & Power [Member]
Segment Reporting Information [Line Items]
Operating revenues	11,194	9,906	25,557	22,960
Operating Segments [Member] | Utility Revenue [Member]
Segment Reporting Information [Line Items]
Operating revenues	379,798	378,421	854,303	840,347
Resource costs	141,244	157,397	334,172	344,265
Other operating expenses	103,071	104,482	208,049	199,009
Depreciation and amortization	66,148	62,806	131,336	125,383
Income (loss) from operations	44,418	27,078	121,935	110,915
Interest expense	35,496	28,565	71,022	56,624
Income taxes	(5,083)	(2,776)	(11,492)	(13,876)
Net income (loss)	20,169	4,721	75,838	75,292
Capital expenditures	126,256	114,659	226,746	210,646
Total Assets	7,200,385		7,200,385		7,240,486
Operating Segments [Member] | Avista Utilities [Member]
Segment Reporting Information [Line Items]
Capital expenditures				207,314
Operating Segments [Member] | Avista Utilities [Member] | Utility Revenue [Member]
Segment Reporting Information [Line Items]
Operating revenues	368,604	368,515	828,746	817,387
Resource costs	140,017	156,221	332,154	342,645
Other operating expenses	99,276	100,782	200,665	191,766
Depreciation and amortization	63,419	60,106	125,883	119,985
Income (loss) from operations	41,257	25,037	111,816	102,816
Interest expense	34,044	27,078	68,118	53,650
Income taxes	(5,556)	(2,565)	(13,504)	(14,925)
Net income (loss)	18,810	3,950	70,437	71,228
Capital expenditures	121,834	111,850	219,598
Total Assets	6,929,611		6,929,611		6,976,164
Operating Segments [Member] | Alaska Electric Light & Power [Member] | Utility Revenue [Member]
Segment Reporting Information [Line Items]
Operating revenues	11,194	9,906	25,557	22,960
Resource costs	1,227	1,176	2,018	1,620
Other operating expenses	3,795	3,700	7,384	7,243
Depreciation and amortization	2,729	2,700	5,453	5,398
Income (loss) from operations	3,161	2,041	10,119	8,099
Interest expense	1,452	1,487	2,904	2,974
Income taxes	473	(211)	2,012	1,049
Net income (loss)	1,359	771	5,401	4,064
Capital expenditures	4,422	2,809	7,148	3,332
Total Assets	270,774		270,774		264,322
Other [Member] | Non-Utility Revenue [Member]
Segment Reporting Information [Line Items]
Operating revenues	139	145	265	265
Resource costs	0	0	0	0
Other operating expenses	749	2,910	1,760	3,866
Depreciation and amortization	0	30	31	62
Income (loss) from operations	(610)	(2,795)	(1,526)	(3,663)
Interest expense	448	137	795	265
Income taxes	(727)	1,777	(946)	2,041
Net income (loss)	(2,685)	6,732	(3,509)	7,726
Capital expenditures	0	342	3	756
Total Assets	189,314		189,314		187,027
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	(318)	(7)	(536)	(10)
Income taxes	0	0	0	0
Net income (loss)	0	0	0	0
Capital expenditures	0	$ 0	0	$ 0
Total Assets	$ (18,384)		$ (18,384)		$ (10,163)