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REGULATORY MATTERS - MPC Integrated Resource Plan (Details) $ in Millions | 1 Months Ended |  |  |  |
--- | --- | --- | --- | --- | ---
Oct. 31, 2023 MW | Dec. 31, 2023 USD ($) | Dec. 31, 2022 USD ($) | Dec. 31, 2021 MW | Dec. 31, 2020 MW
Public Utilities, General Disclosures [Line Items] |  |  |  |  |
Net regulatory assets | $ |  | $ 6,523 | $ 5,833 |  |
Mississippi Power |  |  |  |  |
Public Utilities, General Disclosures [Line Items] |  |  |  |  |
Required fossil-stream generation retirements (in MWs) |  |  |  |  | 950
Net regulatory assets | $ |  | 90 | $ 4 |  |
Approved additional generating capacity (in MW) | 750 |  |  |  |
Mississippi Power | Plant Watson Unit 4 |  |  |  |  |
Public Utilities, General Disclosures [Line Items] |  |  |  |  |
Required fossil-stream generation retirements (in MWs) |  |  |  | 268 |
Mississippi Power | Plant Greene County Units 1 and 2 |  |  |  |  |
Public Utilities, General Disclosures [Line Items] |  |  |  |  |
Required fossil-stream generation retirements (in MWs) |  |  |  | 103 |
Percent ownership |  |  |  | 40.00% |
Mississippi Power | Plant Greene County Units 1 and 2 | Alabama Power |  |  |  |  |
Public Utilities, General Disclosures [Line Items] |  |  |  |  |
Percent ownership |  |  |  | 40.00% |
Mississippi Power | Plant Daniel |  |  |  |  |
Public Utilities, General Disclosures [Line Items] |  |  |  |  |
Required fossil-stream generation retirements (in MWs) |  |  |  | 502 |
Percent ownership |  |  |  | 50.00% |
Net regulatory assets | $ |  | $ 489 |  |  |

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