DERIVATIVES - Energy-Related Derivative Contracts (Details) - Energy-related, Natural Gas MMBTU in Millions	Dec. 31, 2022 MMBTU
Derivative [Line Items]
Net Purchased mmBtu	431
Alabama Power
Derivative [Line Items]
Net Purchased mmBtu	111
Georgia Power
Derivative [Line Items]
Net Purchased mmBtu	125
Mississippi Power
Derivative [Line Items]
Net Purchased mmBtu	94
Southern Power
Derivative [Line Items]
Net Purchased mmBtu	8
Southern Company Gas
Derivative [Line Items]
Net Purchased mmBtu	93
Long | Not Designated as Hedging Instrument | Southern Company Gas
Derivative [Line Items]
Derivative nonmonetary notional amount net long short position volume	98
Short | Not Designated as Hedging Instrument | Southern Company Gas
Derivative [Line Items]
Derivative nonmonetary notional amount net long short position volume	5