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ACQUISITIONS AND DISPOSITIONS - Southern Power Narrative (Details) $ in Millions | 1 Months Ended | 12 Months Ended |
--- | --- | --- | ---
Jan. 31, 2020 USD ($) | Jun. 30, 2019 USD ($) MW | Dec. 31, 2022 | Dec. 31, 2021 USD ($) MW | Dec. 31, 2020 USD ($) | Dec. 31, 2019 USD ($) | May 31, 2019 MW
Asset Acquisition [Line Items] |  |  |  |  |  |  |
Construction work in progress |  |  |  | $ 8,771 | $ 8,697 |  |
Gain (loss) on dispositions |  |  |  | 176 | 66 | $ 2,588 |
Southern Power |  |  |  |  |  |  |
Asset Acquisition [Line Items] |  |  |  |  |  |  |
Construction work in progress |  |  |  | 45 | 127 |  |
Gain (loss) on dispositions |  |  |  | $ 41 | $ 39 | 24 |
Southern Power | Garland |  |  |  |  |  |  |
Asset Acquisition [Line Items] |  |  |  |  |  |  |
Nameplate capacity placed in service (in MWs) | MW |  |  |  | 73 |  |  |
Southern Power | Tranquility Solar Storage |  |  |  |  |  |  |
Asset Acquisition [Line Items] |  |  |  |  |  |  |
Nameplate capacity placed in service (in MWs) | MW |  |  |  | 32 |  |  |
Southern Power | Series of Business Acquisitions |  |  |  |  |  |  |
Asset Acquisition [Line Items] |  |  |  |  |  |  |
Construction costs incurred to date |  |  |  | $ 383 |  |  |
Southern Power | Minimum | Series of Business Acquisitions |  |  |  |  |  |  |
Asset Acquisition [Line Items] |  |  |  |  |  |  |
Aggregate construction costs |  |  |  | 230 |  |  |
Southern Power | Maximum | Series of Business Acquisitions |  |  |  |  |  |  |
Asset Acquisition [Line Items] |  |  |  |  |  |  |
Aggregate construction costs |  |  |  | $ 270 |  |  |
Wind Generating Facility | Southern Power |  |  |  |  |  |  |
Asset Acquisition [Line Items] |  |  |  |  |  |  |
Project qualification for production tax credits, percentage |  |  |  | 100.00% |  |  |
Gain (loss) on dispositions |  |  |  | $ 37 |  | $ 17 |
Gain (loss) on dispositions, after tax |  |  |  | $ 28 |  |  |
Scenario, Forecast | Wind Generating Facility | Southern Power |  |  |  |  |  |  |
Asset Acquisition [Line Items] |  |  |  |  |  |  |
Project qualification for production tax credits, percentage |  |  | 80.00% |  |  |  |
Disposal Group, Disposed of by Sale, Not Discontinued Operations | Nacogdoches Biomass-Fueled Facility | Southern Power |  |  |  |  |  |  |
Asset Acquisition [Line Items] |  |  |  |  |  |  |
Gain (loss) on dispositions |  | $ 23 |  |  |  |  |
Approximate nameplate capacity (in MWs) | MW |  | 115 |  |  |  |  |
Consideration for sale |  | $ 461 |  |  |  |  |
Gain (loss) on dispositions, after tax |  | $ 88 |  |  |  |  |
Disposal Group, Disposed of by Sale, Not Discontinued Operations | Mankato | Southern Power |  |  |  |  |  |  |
Asset Acquisition [Line Items] |  |  |  |  |  |  |
Gain (loss) on dispositions | $ 39 |  |  |  |  |  |
Approximate nameplate capacity (in MWs) | MW |  |  |  |  |  |  | 385
Consideration for sale | 663 |  |  |  |  |  |
Gain (loss) on dispositions, after tax | $ 23 |  |  |  |  |  |

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