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Derivatives - Schedule of Foreign Currency Derivatives (Details) - 9 months ended Sep. 30, 2024 - Foreign currency derivatives € in Millions, $ in Millions | USD ($) | EUR (€)
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Derivative [Line Items] |  |
Pay Notional | $ 2,040 |
Receive Notional | € |  | € 1,750
Fair Value Gain (Loss) | (105) |
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) | $ (15) |
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) | $ (90) |

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