Information by Business Segments - Schedule of Business Segments (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Segment Reporting Information [Line Items]
Operating revenues	$ 1,751,554	$ 1,710,207	$ 1,438,936
Resource costs	702,372	735,862	497,123
Other operating expenses	416,368	416,768	372,052
Depreciation and amortization	265,409	253,142	232,176
Income (loss) from operations	257,690	190,242	228,232
Interest expense	143,299	118,692	106,152
Income tax expense (benefit)	(33,630)	(17,191)	12,031
Net income (loss)	171,180	155,176	147,334
Capital expenditures	498,637	452,829	441,209
Total Assets	7,702,477	7,417,350	6,853,583
Operating Segments [Member] | Utility Revenue [Member]
Segment Reporting Information [Line Items]
Operating revenues	1,750,996	1,709,519	1,438,365
Resource costs	702,372	735,862	497,123
Other operating expenses	413,608	405,165	366,125
Depreciation and amortization	265,329	253,017	231,915
Income (loss) from operations	259,972	201,282	233,849
Interest expense	142,776	118,173	105,725
Income tax expense (benefit)	(32,038)	(25,031)	8,792
Net income (loss)	175,953	125,446	132,782
Capital expenditures	498,637	451,995	439,939
Total Assets	7,532,387	7,240,486	6,723,666
Operating Segments [Member] | Avista Utilities [Member] | Utility Revenue [Member]
Segment Reporting Information [Line Items]
Operating revenues	1,702,857	1,663,815	1,392,999
Resource costs	698,546	732,298	493,289
Other operating expenses	398,523	390,597	352,241
Depreciation and amortization	254,401	242,198	221,552
Income (loss) from operations	242,678	185,582	217,663
Interest expense	136,924	112,213	99,629
Income tax expense (benefit)	(35,353)	(27,368)	6,029
Net income (loss)	167,016	117,901	125,558
Capital expenditures	484,716	443,373	435,887
Total Assets	7,262,704	6,976,164	6,458,244
Operating Segments [Member] | Alaska Electric Light & Power [Member] | Utility Revenue [Member]
Segment Reporting Information [Line Items]
Operating revenues	48,139	45,704	45,366
Resource costs	3,826	3,564	3,834
Other operating expenses	15,085	14,568	13,884
Depreciation and amortization	10,928	10,819	10,363
Income (loss) from operations	17,294	15,700	16,186
Interest expense	5,852	5,960	6,096
Income tax expense (benefit)	3,315	2,337	2,763
Net income (loss)	8,937	7,545	7,224
Capital expenditures	13,921	8,622	4,052
Total Assets	269,683	264,322	265,422
Other [Member] | Non-Utility Revenue [Member]
Segment Reporting Information [Line Items]
Operating revenues	558	688	571
Resource costs	0	0	0
Other operating expenses	2,760	11,603	5,927
Depreciation and amortization	80	125	261
Income (loss) from operations	(2,282)	(11,040)	(5,617)
Interest expense	1,881	791	522
Income tax expense (benefit)	(1,592)	7,840	3,239
Net income (loss)	(4,773)	29,730	14,552
Capital expenditures	0	834	1,270
Total Assets	191,665	187,027	132,158
Intersegment Eliminations [Member]
Segment Reporting Information [Line Items]
Operating revenues	0	0	0
Resource costs	0	0	0
Other operating expenses	0	0	0
Depreciation and amortization	0	0	0
Income (loss) from operations	0	0	0
Interest expense	(1,358)	(272)	(95)
Income tax expense (benefit)	0	0	0
Net income (loss)	0	0	0
Capital expenditures	0	0	0
Total Assets	$ (21,575)	$ (10,163)	$ (2,241)