DERIVATIVES - Energy-Related Derivative Contracts (Details) - Energy-related, Natural Gas MMBTU in Millions	Dec. 31, 2023 MMBTU
Derivative [Line Items]
Net Purchased mmBtu	448.0
Alabama Power
Derivative [Line Items]
Net Purchased mmBtu	118.0
Georgia Power
Derivative [Line Items]
Net Purchased mmBtu	128.0
Mississippi Power
Derivative [Line Items]
Net Purchased mmBtu	93.0
Southern Power
Derivative [Line Items]
Net Purchased mmBtu	7.0
Southern Company Gas
Derivative [Line Items]
Net Purchased mmBtu	102.0
Long | Not Designated as Hedging Instrument | Southern Company Gas
Derivative [Line Items]
Derivative nonmonetary notional amount net long short position volume	112.0
Short | Not Designated as Hedging Instrument | Southern Company Gas
Derivative [Line Items]
Derivative nonmonetary notional amount net long short position volume	10.0