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Regulatory Matters - Schedule of Cost Recovery Clauses (Details) - USD ($) $ in Millions | Sep. 30, 2025 | Dec. 31, 2024
--- | --- | ---
ALABAMA POWER CO | Other regulatory assets, current |  |
Loss Contingencies [Line Items] |  |
Rate ECR | $ 14 | $ 0
ALABAMA POWER CO | Other regulatory assets, deferred |  |
Loss Contingencies [Line Items] |  |
Rate ECR | 69 | 0
ALABAMA POWER CO | Other regulatory liabilities, current |  |
Loss Contingencies [Line Items] |  |
Rate ECR | 0 | 29
GEORGIA POWER CO | Receivables – under recovered retail fuel clause revenues |  |
Loss Contingencies [Line Items] |  |
Fuel Cost Recovery | 487 | 713
GEORGIA POWER CO | Deferred under recovered retail fuel clause revenues |  |
Loss Contingencies [Line Items] |  |
Fuel Cost Recovery | 197 | 453
MISSISSIPPI POWER CO | Wholesale MB |  |
Loss Contingencies [Line Items] |  |
Fuel Cost Recovery | 0 | 0
MISSISSIPPI POWER CO | Deferred under recovered retail fuel clause revenues |  |
Loss Contingencies [Line Items] |  |
Fuel Cost Recovery | 0 | 32
MISSISSIPPI POWER CO | Receivables – customer accounts, net |  |
Loss Contingencies [Line Items] |  |
Fuel Cost Recovery | 30 | 0
MISSISSIPPI POWER CO | Over recovered retail fuel clause revenues |  |
Loss Contingencies [Line Items] |  |
Fuel Cost Recovery | 0 | 32
MISSISSIPPI POWER CO | Other current liabilities | Wholesale MRA |  |
Loss Contingencies [Line Items] |  |
Fuel Cost Recovery | 0 | 19
SOUTHERN Co GAS | Natural gas cost over recovery |  |
Loss Contingencies [Line Items] |  |
Natural gas cost under recovery | $ 163 | $ 193

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