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Derivatives - Schedule of Energy-Related Derivatives (Details) - Energy-related, Natural Gas MMBTU in Millions	Sep. 30, 2025 MMBTU
Energy-related derivative contracts
Net Purchased mmBtu	443.0
ALABAMA POWER CO
Energy-related derivative contracts
Net Purchased mmBtu	132.0
GEORGIA POWER CO
Energy-related derivative contracts
Net Purchased mmBtu	123.0
MISSISSIPPI POWER CO
Energy-related derivative contracts
Net Purchased mmBtu	101.0
SOUTHERN POWER CO
Energy-related derivative contracts
Net Purchased mmBtu	9.0
SOUTHERN Co GAS
Energy-related derivative contracts
Net Purchased mmBtu	78.0
SOUTHERN Co GAS | Energy-related derivatives not designated as hedging instruments | Long
Energy-related derivative contracts
Derivative nonmonetary notional amount net long short position volume	96.0
SOUTHERN Co GAS | Energy-related derivatives not designated as hedging instruments | Short
Energy-related derivative contracts
Derivative nonmonetary notional amount net long short position volume	18.0

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Derivative Nonmonetary Notional Amount Net Long Short Position Volume

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Energy-related derivative contracts for the registrants.

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Net Quantity Purchase Of Derivatives Not Designated As Hedges

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