Revenue - Disaggregation of Revenue (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2024	Jun. 30, 2023	Jun. 30, 2024	Jun. 30, 2023
Disaggregation of Revenue [Line Items]
Alternative revenue programs	$ 16,171	$ 5,513	$ 19,054	$ (13,525)
Total utility revenues	402,032	379,798	1,011,426	854,303
Non-utility revenues	40	139	62	265
Total operating revenues	402,072	379,937	1,011,488	854,568
Residential Electric [Member]
Disaggregation of Revenue [Line Items]
Revenue from contract with customer including assessed tax	97,357	90,917	246,540	220,621
Commercial Electric [Member]
Disaggregation of Revenue [Line Items]
Revenue from contract with customer including assessed tax	91,768	87,890	191,642	176,382
Industrial Electric [Member]
Disaggregation of Revenue [Line Items]
Revenue from contract with customer including assessed tax	30,038	27,956	58,104	53,123
Public Street and Highway Lighting Electric [Member]
Disaggregation of Revenue [Line Items]
Revenue from contract with customer including assessed tax	2,317	2,041	4,547	4,060
Retail Electric [Member]
Disaggregation of Revenue [Line Items]
Revenue from contract with customer including assessed tax	221,480	208,804	500,833	454,186
Transmission Electric [Member]
Disaggregation of Revenue [Line Items]
Revenue from contract with customer including assessed tax	9,538	8,475	19,130	16,422
Other Electric Revenues from Contracts With Customers [Member]
Disaggregation of Revenue [Line Items]
Revenue from contract with customer including assessed tax	8,334	6,934	24,395	24,227
Electric [Member]
Disaggregation of Revenue [Line Items]
Revenue from contract with customer including assessed tax	239,352	224,213	544,358	494,835
Avista Utilities [Member]
Disaggregation of Revenue [Line Items]
Revenue from contract with customer including assessed tax	319,373	294,129	818,755	772,904
Derivative revenues	48,605	66,580	138,185	63,518
Alternative revenue programs	16,171	5,513	19,054	(13,525)
Other utility revenues	6,665	2,382	9,756	5,849
Total utility revenues	390,814	368,604	985,750	828,746
Avista Utilities [Member] | Residential Electric [Member]
Disaggregation of Revenue [Line Items]
Revenue from contract with customer including assessed tax	92,809	86,499	234,838	209,322
Avista Utilities [Member] | Commercial Electric [Member]
Disaggregation of Revenue [Line Items]
Revenue from contract with customer including assessed tax	85,344	81,346	178,136	162,572
Avista Utilities [Member] | Industrial Electric [Member]
Disaggregation of Revenue [Line Items]
Revenue from contract with customer including assessed tax	30,038	27,956	58,104	53,123
Avista Utilities [Member] | Public Street and Highway Lighting Electric [Member]
Disaggregation of Revenue [Line Items]
Revenue from contract with customer including assessed tax	2,254	1,980	4,418	3,935
Avista Utilities [Member] | Retail Electric [Member]
Disaggregation of Revenue [Line Items]
Revenue from contract with customer including assessed tax	210,445	197,781	475,496	428,952
Avista Utilities [Member] | Transmission Electric [Member]
Disaggregation of Revenue [Line Items]
Revenue from contract with customer including assessed tax	9,538	8,475	19,130	16,422
Avista Utilities [Member] | Other Electric Revenues from Contracts With Customers [Member]
Disaggregation of Revenue [Line Items]
Revenue from contract with customer including assessed tax	8,334	6,934	24,395	24,227
Avista Utilities [Member] | Electric [Member]
Disaggregation of Revenue [Line Items]
Revenue from contract with customer including assessed tax	228,317	213,190	519,021	469,601
Avista Utilities [Member] | Residential Natural Gas [Member]
Disaggregation of Revenue [Line Items]
Revenue from contract with customer including assessed tax	54,427	48,004	187,397	188,840
Avista Utilities [Member] | Commercial Natural Gas [Member]
Disaggregation of Revenue [Line Items]
Revenue from contract with customer including assessed tax	29,293	25,477	97,292	97,802
Avista Utilities [Member] | Industrial and Interruptible Natural Gas [Member]
Disaggregation of Revenue [Line Items]
Revenue from contract with customer including assessed tax	3,195	4,128	7,160	9,656
Avista Utilities [Member] | Retail Natural Gas [Member]
Disaggregation of Revenue [Line Items]
Revenue from contract with customer including assessed tax	86,915	77,609	291,849	296,298
Avista Utilities [Member] | Transportation Natural Gas [Member]
Disaggregation of Revenue [Line Items]
Revenue from contract with customer including assessed tax	2,734	1,923	5,072	4,192
Avista Utilities [Member] | Other Natural Gas Revenues from Contracts With Customers [Member]
Disaggregation of Revenue [Line Items]
Revenue from contract with customer including assessed tax	1,407	1,407	2,813	2,813
Avista Utilities [Member] | Natural Gas [Member]
Disaggregation of Revenue [Line Items]
Revenue from contract with customer including assessed tax	91,056	80,939	299,734	303,303
Alaska Electric Light & Power [Member]
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	11,035	11,023	25,337	25,234
Other utility revenues	183	171	339	323
Total utility revenues	11,218	11,194	25,676	25,557
Alaska Electric Light & Power [Member] | Residential Electric [Member]
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	4,548	4,418	11,702	11,299
Alaska Electric Light & Power [Member] | Commercial Electric [Member]
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	6,424	6,544	13,506	13,810
Alaska Electric Light & Power [Member] | Public Street and Highway Lighting Electric [Member]
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	63	61	129	125
Alaska Electric Light & Power [Member] | Retail Electric [Member]
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	11,035	11,023	25,337	25,234
Alaska Electric Light & Power [Member] | Electric [Member]
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	11,035	11,023	25,337	25,234
Corporate and Other [Member]
Disaggregation of Revenue [Line Items]
Non-utility revenues	$ 40	$ 139	$ 62	$ 265