Derivatives - Schedule of Energy-Related Derivatives (Details) - Energy-related, Natural Gas MMBTU in Millions	Jun. 30, 2024 MMBTU
Energy-related derivative contracts
Net Purchased mmBtu	464.0
ALABAMA POWER CO
Energy-related derivative contracts
Net Purchased mmBtu	124.0
GEORGIA POWER CO
Energy-related derivative contracts
Net Purchased mmBtu	132.0
MISSISSIPPI POWER CO
Energy-related derivative contracts
Net Purchased mmBtu	107.0
SOUTHERN POWER CO
Energy-related derivative contracts
Net Purchased mmBtu	7.0
SOUTHERN Co GAS
Energy-related derivative contracts
Net Purchased mmBtu	94.0
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	103.0
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	9.0