Property, Plant And Equipment - Schedule of Major Classifications of Property, Plant And Equipment (Details) - USD ($) $ in Thousands	Dec. 31, 2021	Dec. 31, 2020
Public Utility, Property, Plant and Equipment [Line Items]
Construction work-in-progress (CWIP) and other	$ 205,405	$ 175,767
Total	7,371,985	6,985,564
Other Property	280,543	263,639
Total	7,389,803	7,001,958
Avista Utilities [Member]
Public Utility, Property, Plant and Equipment [Line Items]
Total	7,199,017	6,815,891
Common Plant	740,339	712,609
Avista Utilities [Member] | Electricity [Member]
Public Utility, Property, Plant and Equipment [Line Items]
Production	1,494,371	1,457,497
Transmission	945,624	862,987
Distribution	2,093,937	1,978,868
Construction work-in-progress (CWIP) and other	424,733	384,372
Total	4,958,665	4,683,724
Avista Utilities [Member] | Natural Gas [Member]
Public Utility, Property, Plant and Equipment [Line Items]
Distribution	1,356,477	1,282,563
Construction work-in-progress (CWIP) and other	87,852	83,644
Total	1,500,013	1,419,558
Natural gas underground storage	55,684	53,351
Alaska Electric Light & Power [Member]
Public Utility, Property, Plant and Equipment [Line Items]
Total	172,968	169,673
Common Plant	9,726	9,687
Alaska Electric Light & Power [Member] | Electricity [Member]
Public Utility, Property, Plant and Equipment [Line Items]
Production	106,094	105,076
Transmission	22,691	22,419
Distribution	27,138	25,814
Construction work-in-progress (CWIP) and other	7,319	6,677
Total	163,242	159,986
Corporate and Other [Member]
Public Utility, Property, Plant and Equipment [Line Items]
Other Property	$ 17,818	$ 16,394