Derivatives - Schedule of Foreign Currency Derivatives (Details) - 9 months ended Sep. 30, 2023 - Foreign currency derivatives € in Millions, $ in Millions |
USD ($) |
EUR (€) |
|---|---|---|
| Derivative [Line Items] | ||
| Pay Notional | $ 2,040 | |
| Receive Notional | € | € 1,750 | |
| Fair Value Gain (Loss) | (192) | |
| Cash Flow Hedges of Forecasted Debt | SOUTHERN POWER CO | ||
| Derivative [Line Items] | ||
| Pay Notional | $ 564 | |
| Pay Rate | 3.78% | |
| Receive Notional | € | 500 | |
| Receive Rate | 1.85% | |
| Fair Value Gain (Loss) | $ (42) | |
| Fair Value Hedges of Existing Debt | Southern Company parent | ||
| Derivative [Line Items] | ||
| Pay Notional | $ 1,476 | |
| Pay Rate | 3.39% | |
| Receive Notional | € | € 1,250 | |
| Receive Rate | 1.88% | |
| Fair Value Gain (Loss) | $ (150) |