Derivatives - Schedule of Energy-Related Derivatives (Details) - Energy-related, Natural Gas MMBTU in Millions	Mar. 31, 2023 MMBTU
Energy-related derivative contracts
Net Purchased mmBtu	437.0
ALABAMA POWER CO
Energy-related derivative contracts
Net Purchased mmBtu	111.0
GEORGIA POWER CO
Energy-related derivative contracts
Net Purchased mmBtu	122.0
MISSISSIPPI POWER CO
Energy-related derivative contracts
Net Purchased mmBtu	86.0
SOUTHERN POWER CO
Energy-related derivative contracts
Net Purchased mmBtu	11.0
SOUTHERN Co GAS
Energy-related derivative contracts
Net Purchased mmBtu	107.0
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	113.6
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	6.6