Revenue - Disaggregation of Revenue (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2023	Sep. 30, 2022
Disaggregation of Revenue [Line Items]
Revenues	$ 379,626	$ 359,446	$ 1,234,194	$ 1,200,058
Alternative revenue programs	3,578	(5,850)	(9,947)	(28,420)
Total utility revenues	379,524	359,292	1,233,827	1,199,639
Unregulated Operating Revenue	102	154	367	419
Residential Electric [Member]
Disaggregation of Revenue [Line Items]
Revenue from contract with customer including assessed tax	99,067	97,574	319,688	313,302
Commercial Electric [Member]
Disaggregation of Revenue [Line Items]
Revenue from contract with customer including assessed tax	96,219	95,750	272,601	272,518
Industrial Electric [Member]
Disaggregation of Revenue [Line Items]
Revenue from contract with customer including assessed tax	29,584	30,090	82,707	82,235
Public Street and Highway Lighting Electric [Member]
Disaggregation of Revenue [Line Items]
Revenue from contract with customer including assessed tax	2,072	1,874	6,132	5,769
Retail Electric [Member]
Disaggregation of Revenue [Line Items]
Revenue from contract with customer including assessed tax	226,942	225,288	681,128	673,824
Transmission Electric [Member]
Disaggregation of Revenue [Line Items]
Revenue from contract with customer including assessed tax	7,721	9,662	24,143	22,764
Other Electric Revenues from Contracts With Customers [Member]
Disaggregation of Revenue [Line Items]
Revenue from contract with customer including assessed tax	9,353	11,457	33,580	27,628
Electric [Member]
Disaggregation of Revenue [Line Items]
Revenue from contract with customer including assessed tax	244,016	246,407	738,851	724,216
Avista Utilities [Member]
Disaggregation of Revenue [Line Items]
Derivative revenues	77,562	76,248	141,080	218,024
Alternative revenue programs	3,578	(5,850)	(9,947)	(28,420)
Deferrals and amortizations for rate refunds to customers	124	156	769	25
Other utility revenues	2,588	2,113	7,792	7,166
Total utility revenues	369,673	349,655	1,198,419	1,167,042
Revenue from contract with customer including assessed tax	285,821	276,988	1,058,725	970,247
Avista Utilities [Member] | Residential Electric [Member]
Disaggregation of Revenue [Line Items]
Revenue from contract with customer including assessed tax	95,881	94,451	305,203	299,562
Avista Utilities [Member] | Commercial Electric [Member]
Disaggregation of Revenue [Line Items]
Revenue from contract with customer including assessed tax	89,772	89,411	252,344	253,694
Avista Utilities [Member] | Industrial Electric [Member]
Disaggregation of Revenue [Line Items]
Revenue from contract with customer including assessed tax	29,584	30,090	82,707	82,235
Avista Utilities [Member] | Public Street and Highway Lighting Electric [Member]
Disaggregation of Revenue [Line Items]
Revenue from contract with customer including assessed tax	2,005	1,810	5,940	5,586
Avista Utilities [Member] | Retail Electric [Member]
Disaggregation of Revenue [Line Items]
Revenue from contract with customer including assessed tax	217,242	215,762	646,194	641,077
Avista Utilities [Member] | Transmission Electric [Member]
Disaggregation of Revenue [Line Items]
Revenue from contract with customer including assessed tax	7,721	9,662	24,143	22,764
Avista Utilities [Member] | Other Electric Revenues from Contracts With Customers [Member]
Disaggregation of Revenue [Line Items]
Revenue from contract with customer including assessed tax	9,353	11,457	33,580	27,628
Avista Utilities [Member] | Electric [Member]
Disaggregation of Revenue [Line Items]
Revenue from contract with customer including assessed tax	234,316	236,881	703,917	691,469
Avista Utilities [Member] | Residential Natural Gas [Member]
Disaggregation of Revenue [Line Items]
Revenue from contract with customer including assessed tax	29,372	22,960	218,212	174,655
Avista Utilities [Member] | Commercial Natural Gas [Member]
Disaggregation of Revenue [Line Items]
Revenue from contract with customer including assessed tax	15,381	11,978	113,183	86,335
Avista Utilities [Member] | Industrial and Interruptible Natural Gas [Member]
Disaggregation of Revenue [Line Items]
Revenue from contract with customer including assessed tax	3,480	1,930	13,136	7,238
Avista Utilities [Member] | Retail Natural Gas [Member]
Disaggregation of Revenue [Line Items]
Revenue from contract with customer including assessed tax	48,233	36,868	344,531	268,228
Avista Utilities [Member] | Transportation Natural Gas [Member]
Disaggregation of Revenue [Line Items]
Revenue from contract with customer including assessed tax	1,866	1,832	6,058	6,331
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	1,406	1,407	4,219	4,219
Avista Utilities [Member] | Natural Gas [Member]
Disaggregation of Revenue [Line Items]
Revenue from contract with customer including assessed tax	51,505	40,107	354,808	278,778
Alaska Electric Light & Power [Member]
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	9,700	9,526	34,934	32,747
Deferrals and amortizations for rate refunds to customers		(49)		(614)
Other utility revenues	151	160	474	464
Total utility revenues	9,851	9,637	35,408	32,597
Alaska Electric Light & Power [Member] | Residential Electric [Member]
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	3,186	3,123	14,485	13,740
Alaska Electric Light & Power [Member] | Commercial Electric [Member]
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	6,447	6,339	20,257	18,824
Alaska Electric Light & Power [Member] | Public Street and Highway Lighting Electric [Member]
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	67	64	192	183
Alaska Electric Light & Power [Member] | Retail Electric [Member]
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	9,700	9,526	34,934	32,747
Alaska Electric Light & Power [Member] | Electric [Member]
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	9,700	9,526	34,934	32,747
Corporate and Other [Member]
Disaggregation of Revenue [Line Items]
Unregulated Operating Revenue	$ 102	$ 154	$ 367	$ 419