SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES - Income and Other Taxes (Narrative) (Details) - USD ($) $ in Millions |
12 Months Ended | ||
|---|---|---|---|
Dec. 31, 2024 |
Dec. 31, 2023 |
Dec. 31, 2022 |
|
| Southern Power | |||
| Tax Credit Carryforward [Line Items] | |||
| Percentage reduction in tax basis of assets | 50.00% | ||
| Southern Company Gas | |||
| Tax Credit Carryforward [Line Items] | |||
| Excise taxes collected | $ 115 | $ 133 | $ 162 |
| Included In Operating Expenses | Southern Company Gas | |||
| Tax Credit Carryforward [Line Items] | |||
| Excise taxes collected | $ 112 | $ 129 | $ 158 |