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Revenue - Disaggregation of Revenue (Details) - USD ($) $ in Thousands | 3 Months Ended | 9 Months Ended
--- | --- | ---
Sep. 30, 2024 | Sep. 30, 2023 | Sep. 30, 2024 | Sep. 30, 2023
Disaggregation of Revenue [Line Items] |  |  |  |
Alternative revenue programs | $ 3,978 | $ 3,578 | $ 23,032 | $ (9,947)
Total utility revenues | 393,565 | 379,524 | 1,404,991 | 1,233,827
Non-utility revenues | 177 | 102 | 239 | 367
Total operating revenues | 393,742 | 379,626 | 1,405,230 | 1,234,194
Residential Electric [Member] |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |
Revenue from contract with customer including assessed tax | 113,772 | 99,067 | 360,312 | 319,688
Commercial Electric [Member] |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |
Revenue from contract with customer including assessed tax | 103,702 | 96,219 | 295,344 | 272,601
Industrial Electric [Member] |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |
Revenue from contract with customer including assessed tax | 36,910 | 29,584 | 95,014 | 82,707
Public Street and Highway Lighting Electric [Member] |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |
Revenue from contract with customer including assessed tax | 2,255 | 2,072 | 6,802 | 6,132
Retail Electric [Member] |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |
Revenue from contract with customer including assessed tax | 256,639 | 226,942 | 757,472 | 681,128
Transmission Electric [Member] |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |
Revenue from contract with customer including assessed tax | 9,250 | 7,721 | 28,380 | 24,143
Other Electric Revenues from Contracts With Customers [Member] |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |
Revenue from contract with customer including assessed tax | 8,062 | 9,353 | 32,457 | 33,580
Electric [Member] |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |
Revenue from contract with customer including assessed tax | 273,951 | 244,016 | 818,309 | 738,851
Avista Utilities [Member] |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |
Revenue from contract with customer including assessed tax | 318,171 | 285,821 | 1,136,926 | 1,058,725
Derivative revenues | 56,462 | 77,562 | 194,647 | 141,080
Alternative revenue programs | 3,978 | 3,578 | 23,032 | (9,947)
Other utility revenues | 5,135 | 2,712 | 14,891 | 8,561
Total utility revenues | 383,746 | 369,673 | 1,369,496 | 1,198,419
Avista Utilities [Member] | Residential Electric [Member] |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |
Revenue from contract with customer including assessed tax | 110,328 | 95,881 | 345,166 | 305,203
Avista Utilities [Member] | Commercial Electric [Member] |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |
Revenue from contract with customer including assessed tax | 97,389 | 89,772 | 275,525 | 252,344
Avista Utilities [Member] | Industrial Electric [Member] |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |
Revenue from contract with customer including assessed tax | 36,910 | 29,584 | 95,014 | 82,707
Avista Utilities [Member] | Public Street and Highway Lighting Electric [Member] |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |
Revenue from contract with customer including assessed tax | 2,186 | 2,005 | 6,604 | 5,940
Avista Utilities [Member] | Retail Electric [Member] |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |
Revenue from contract with customer including assessed tax | 246,813 | 217,242 | 722,309 | 646,194
Avista Utilities [Member] | Transmission Electric [Member] |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |
Revenue from contract with customer including assessed tax | 9,250 | 7,721 | 28,380 | 24,143
Avista Utilities [Member] | Other Electric Revenues from Contracts With Customers [Member] |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |
Revenue from contract with customer including assessed tax | 8,062 | 9,353 | 32,457 | 33,580
Avista Utilities [Member] | Electric [Member] |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |
Revenue from contract with customer including assessed tax | 264,125 | 234,316 | 783,146 | 703,917
Avista Utilities [Member] | Residential Natural Gas [Member] |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |
Revenue from contract with customer including assessed tax | 30,285 | 29,372 | 217,682 | 218,212
Avista Utilities [Member] | Commercial Natural Gas [Member] |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |
Revenue from contract with customer including assessed tax | 17,203 | 15,381 | 114,495 | 113,183
Avista Utilities [Member] | Industrial and Interruptible Natural Gas [Member] |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |
Revenue from contract with customer including assessed tax | 2,720 | 3,480 | 9,880 | 13,136
Avista Utilities [Member] | Retail Natural Gas [Member] |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |
Revenue from contract with customer including assessed tax | 50,208 | 48,233 | 342,057 | 344,531
Avista Utilities [Member] | Transportation Natural Gas [Member] |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |
Revenue from contract with customer including assessed tax | 2,432 | 1,866 | 7,504 | 6,058
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 | 1,406 | 4,219 | 4,219
Avista Utilities [Member] | Natural Gas [Member] |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |
Revenue from contract with customer including assessed tax | 54,046 | 51,505 | 353,780 | 354,808
Alaska Electric Light & Power [Member] |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |
Revenue from contracts with customers | 9,826 | 9,700 | 35,163 | 34,934
Deferrals and amortizations for rate refunds to customers | (183) |  | (183) |
Other utility revenues | 176 | 151 | 515 | 474
Total utility revenues | 9,819 | 9,851 | 35,495 | 35,408
Alaska Electric Light & Power [Member] | Residential Electric [Member] |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |
Revenue from contracts with customers | 3,444 | 3,186 | 15,146 | 14,485
Alaska Electric Light & Power [Member] | Commercial Electric [Member] |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |
Revenue from contracts with customers | 6,313 | 6,447 | 19,819 | 20,257
Alaska Electric Light & Power [Member] | Public Street and Highway Lighting Electric [Member] |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |
Revenue from contracts with customers | 69 | 67 | 198 | 192
Alaska Electric Light & Power [Member] | Retail Electric [Member] |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |
Revenue from contracts with customers | 9,826 | 9,700 | 35,163 | 34,934
Alaska Electric Light & Power [Member] | Electric [Member] |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |
Revenue from contracts with customers | 9,826 | 9,700 | 35,163 | 34,934
Corporate and Other [Member] |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |
Non-utility revenues | $ 177 | $ 102 | $ 239 | $ 367

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