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Contingencies - Other Matters (Details) - USD ($) $ in Millions | 1 Months Ended | 11 Months Ended
--- | --- | ---
Aug. 31, 2022 | Apr. 30, 2019 | Jun. 30, 2023
Loss Contingencies [Line Items] |  |  |
Estimated additional interest expense |  |  | $ 1
ALABAMA POWER CO | AT&T |  |  |
Loss Contingencies [Line Items] |  |  |
Potential refund amount owed |  | $ 87 |
Refund payment period |  | 6 years |
MISSISSIPPI POWER CO |  |  |
Loss Contingencies [Line Items] |  |  |
Estimate of possible loss | $ 28 |  |

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