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Revenue - Disaggregation of Revenue (Details) - USD ($) $ in Millions | 3 Months Ended
--- | ---
Mar. 31, 2025 | Mar. 31, 2024
Disaggregation of Revenue [Line Items] |  |
Alternative revenue programs | $ (8) | $ 3
Total operating revenues | 617 | 609
Residential Electric [Member] |  |
Disaggregation of Revenue [Line Items] |  |
Revenue from contract with customer including assessed tax | 172 | 149
Commercial Electric [Member] |  |
Disaggregation of Revenue [Line Items] |  |
Revenue from contract with customer including assessed tax | 109 | 100
Industrial Electric [Member] |  |
Disaggregation of Revenue [Line Items] |  |
Revenue from contract with customer including assessed tax | 35 | 28
Public Street and Highway Lighting Electric [Member] |  |
Disaggregation of Revenue [Line Items] |  |
Revenue from contract with customer including assessed tax | 2 | 2
Retail Electric [Member] |  |
Disaggregation of Revenue [Line Items] |  |
Revenue from contract with customer including assessed tax | 318 | 279
Transmission Electric [Member] |  |
Disaggregation of Revenue [Line Items] |  |
Revenue from contract with customer including assessed tax | 9 | 10
Other Electric Revenues from Contracts With Customers [Member] |  |
Disaggregation of Revenue [Line Items] |  |
Revenue from contract with customer including assessed tax | 8 | 16
Electric [Member] |  |
Disaggregation of Revenue [Line Items] |  |
Revenue from contract with customer including assessed tax | 335 | 305
Avista Utilities [Member] |  |
Disaggregation of Revenue [Line Items] |  |
Revenue from contract with customer including assessed tax | 526 | 499
Derivative revenues | 61 | 90
Alternative revenue programs | (8) | 3
Other utility revenues | 25 | 3
Total utility revenues | 604 | 595
Avista Utilities [Member] | Residential Electric [Member] |  |
Disaggregation of Revenue [Line Items] |  |
Revenue from contract with customer including assessed tax | 165 | 142
Avista Utilities [Member] | Commercial Electric [Member] |  |
Disaggregation of Revenue [Line Items] |  |
Revenue from contract with customer including assessed tax | 103 | 93
Avista Utilities [Member] | Industrial Electric [Member] |  |
Disaggregation of Revenue [Line Items] |  |
Revenue from contract with customer including assessed tax | 35 | 28
Avista Utilities [Member] | Public Street and Highway Lighting Electric [Member] |  |
Disaggregation of Revenue [Line Items] |  |
Revenue from contract with customer including assessed tax | 2 | 2
Avista Utilities [Member] | Retail Electric [Member] |  |
Disaggregation of Revenue [Line Items] |  |
Revenue from contract with customer including assessed tax | 305 | 265
Avista Utilities [Member] | Transmission Electric [Member] |  |
Disaggregation of Revenue [Line Items] |  |
Revenue from contract with customer including assessed tax | 9 | 10
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 | 16
Avista Utilities [Member] | Electric [Member] |  |
Disaggregation of Revenue [Line Items] |  |
Revenue from contract with customer including assessed tax | 322 | 291
Avista Utilities [Member] | Residential Natural Gas [Member] |  |
Disaggregation of Revenue [Line Items] |  |
Revenue from contract with customer including assessed tax | 129 | 133
Avista Utilities [Member] | Commercial Natural Gas [Member] |  |
Disaggregation of Revenue [Line Items] |  |
Revenue from contract with customer including assessed tax | 65 | 68
Avista Utilities [Member] | Industrial and Interruptible Natural Gas [Member] |  |
Disaggregation of Revenue [Line Items] |  |
Revenue from contract with customer including assessed tax | 4 | 4
Avista Utilities [Member] | Retail Natural Gas [Member] |  |
Disaggregation of Revenue [Line Items] |  |
Revenue from contract with customer including assessed tax | 198 | 205
Avista Utilities [Member] | Transportation Natural Gas [Member] |  |
Disaggregation of Revenue [Line Items] |  |
Revenue from contract with customer including assessed tax | 5 | 2
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 | 1
Avista Utilities [Member] | Natural Gas [Member] |  |
Disaggregation of Revenue [Line Items] |  |
Revenue from contract with customer including assessed tax | 204 | 208
Alaska Electric Light & Power [Member] |  |
Disaggregation of Revenue [Line Items] |  |
Revenue from contracts with customers | 13 | 14
Alaska Electric Light & Power [Member] | Residential Electric [Member] |  |
Disaggregation of Revenue [Line Items] |  |
Revenue from contracts with customers | 7 | 7
Alaska Electric Light & Power [Member] | Commercial Electric [Member] |  |
Disaggregation of Revenue [Line Items] |  |
Revenue from contracts with customers | 6 | 7
Alaska Electric Light & Power [Member] | Industrial Electric [Member] |  |
Disaggregation of Revenue [Line Items] |  |
Revenue from contract with customer including assessed tax | 0 | 0
Alaska Electric Light & Power [Member] | Public Street and Highway Lighting Electric [Member] |  |
Disaggregation of Revenue [Line Items] |  |
Revenue from contracts with customers | 0 | 0
Alaska Electric Light & Power [Member] | Retail Electric [Member] |  |
Disaggregation of Revenue [Line Items] |  |
Revenue from contracts with customers | 13 | 14
Alaska Electric Light & Power [Member] | Transmission Electric [Member] |  |
Disaggregation of Revenue [Line Items] |  |
Revenue from contract with customer including assessed tax | 0 | 0
Alaska Electric Light & Power [Member] | Other Electric Revenues from Contracts With Customers [Member] |  |
Disaggregation of Revenue [Line Items] |  |
Revenue from contract with customer including assessed tax | 0 | 0
Alaska Electric Light & Power [Member] | Electric [Member] |  |
Disaggregation of Revenue [Line Items] |  |
Revenue from contracts with customers | $ 13 | $ 14

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