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Revenue - Disaggregation of Revenue (Details) - USD ($) $ in Millions | 12 Months Ended
--- | ---
Dec. 31, 2024 | Dec. 31, 2023 | Dec. 31, 2022
Disaggregation of Revenue [Line Items] |  |  |
Alternative revenue programs | $ 35 | $ 5 | $ (34)
Total utility revenues | 1,937 | 1,751 | 1,709
Non-utility revenues | 1 | 1 | 1
Total operating revenues | 1,938 | 1,752 | 1,710
Residential Electric [Member] |  |  |
Disaggregation of Revenue [Line Items] |  |  |
Revenue from contract with customer including assessed tax | 495 | 445 | 435
Commercial and Governmental Electric [Member] |  |  |
Disaggregation of Revenue [Line Items] |  |  |
Revenue from contract with customer including assessed tax | 396 | 371 | 365
Industrial Electric [Member] |  |  |
Disaggregation of Revenue [Line Items] |  |  |
Revenue from contract with customer including assessed tax | 131 | 110 | 108
Public Street and Highway Lighting Electric [Member] |  |  |
Disaggregation of Revenue [Line Items] |  |  |
Revenue from contract with customer including assessed tax | 9 | 8 | 7
Retail Electric [Member] |  |  |
Disaggregation of Revenue [Line Items] |  |  |
Revenue from contract with customer including assessed tax | 1,031 | 934 | 915
Transmission Electric [Member] |  |  |
Disaggregation of Revenue [Line Items] |  |  |
Revenue from contract with customer including assessed tax | 38 | 33 | 32
Other Electric Revenues from Contracts With Customers [Member] |  |  |
Disaggregation of Revenue [Line Items] |  |  |
Revenue from contract with customer including assessed tax | 40 | 45 | 50
Electric [Member] |  |  |
Disaggregation of Revenue [Line Items] |  |  |
Revenue from contract with customer including assessed tax | 1,109 | 1,012 | 997
Other Non-Reportable Segment Items [Member] | Other Revenues [Member] |  |  |
Disaggregation of Revenue [Line Items] |  |  |
Non-utility revenues | 1 | 1 | 1
Avista Utilities [Member] |  |  |
Disaggregation of Revenue [Line Items] |  |  |
Revenue from contract with customer including assessed tax | 1,570 | 1,486 | 1,400
Derivative revenues | 249 | 199 | 286
Alternative revenue programs | 35 | 5 | (34)
Other utility revenues | 33 | 13 | 11
Total utility revenues | 1,887 | 1,703 | 1,663
Avista Utilities [Member] | Residential Electric [Member] |  |  |
Disaggregation of Revenue [Line Items] |  |  |
Revenue from contract with customer including assessed tax | 473 | 425 | 415
Avista Utilities [Member] | Commercial and Governmental Electric [Member] |  |  |
Disaggregation of Revenue [Line Items] |  |  |
Revenue from contract with customer including assessed tax | 369 | 344 | 339
Avista Utilities [Member] | Industrial Electric [Member] |  |  |
Disaggregation of Revenue [Line Items] |  |  |
Revenue from contract with customer including assessed tax | 131 | 110 | 108
Avista Utilities [Member] | Public Street and Highway Lighting Electric [Member] |  |  |
Disaggregation of Revenue [Line Items] |  |  |
Revenue from contract with customer including assessed tax | 9 | 8 | 7
Avista Utilities [Member] | Retail Electric [Member] |  |  |
Disaggregation of Revenue [Line Items] |  |  |
Revenue from contract with customer including assessed tax | 982 | 887 | 869
Avista Utilities [Member] | Transmission Electric [Member] |  |  |
Disaggregation of Revenue [Line Items] |  |  |
Revenue from contract with customer including assessed tax | 38 | 33 | 32
Avista Utilities [Member] | Other Electric Revenues from Contracts With Customers [Member] |  |  |
Disaggregation of Revenue [Line Items] |  |  |
Revenue from contract with customer including assessed tax | 40 | 45 | 50
Avista Utilities [Member] | Electric [Member] |  |  |
Disaggregation of Revenue [Line Items] |  |  |
Revenue from contract with customer including assessed tax | 1,060 | 965 | 951
Avista Utilities [Member] | Residential Natural Gas [Member] |  |  |
Disaggregation of Revenue [Line Items] |  |  |
Revenue from contract with customer including assessed tax | 317 | 326 | 284
Avista Utilities [Member] | Commercial Natural Gas [Member] |  |  |
Disaggregation of Revenue [Line Items] |  |  |
Revenue from contract with customer including assessed tax | 163 | 164 | 140
Avista Utilities [Member] | Industrial and Interruptible Natural Gas [Member] |  |  |
Disaggregation of Revenue [Line Items] |  |  |
Revenue from contract with customer including assessed tax | 13 | 17 | 10
Avista Utilities [Member] | Retail Natural Gas [Member] |  |  |
Disaggregation of Revenue [Line Items] |  |  |
Revenue from contract with customer including assessed tax | 493 | 507 | 434
Avista Utilities [Member] | Transportation Natural Gas [Member] |  |  |
Disaggregation of Revenue [Line Items] |  |  |
Revenue from contract with customer including assessed tax | 11 | 8 | 9
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 | 6 | 6 | 6
Avista Utilities [Member] | Natural Gas [Member] |  |  |
Disaggregation of Revenue [Line Items] |  |  |
Revenue from contract with customer including assessed tax | 510 | 521 | 449
Alaska Electric Light & Power [Member] |  |  |
Disaggregation of Revenue [Line Items] |  |  |
Revenue from contracts with customers | 49 | 47 | 46
Other utility revenues | 1 | 1 |
Total utility revenues | 50 | 48 | 46
Alaska Electric Light & Power [Member] | Residential Electric [Member] |  |  |
Disaggregation of Revenue [Line Items] |  |  |
Revenue from contracts with customers | 22 | 20 | 20
Alaska Electric Light & Power [Member] | Commercial and Governmental Electric [Member] |  |  |
Disaggregation of Revenue [Line Items] |  |  |
Revenue from contracts with customers | 27 | 27 | 26
Alaska Electric Light & Power [Member] | Retail Electric [Member] |  |  |
Disaggregation of Revenue [Line Items] |  |  |
Revenue from contracts with customers | 49 | 47 | 46
Alaska Electric Light & Power [Member] | Electric [Member] |  |  |
Disaggregation of Revenue [Line Items] |  |  |
Revenue from contracts with customers | $ 49 | $ 47 | $ 46

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