DERIVATIVES - Energy-Related Derivative Contracts (Details) - Energy-related, Natural Gas MMBTU in Millions	Dec. 31, 2025 MMBTU
Derivative [Line Items]
Net Purchased mmBtu	431.0
Alabama Power
Derivative [Line Items]
Net Purchased mmBtu	126.0
Georgia Power
Derivative [Line Items]
Net Purchased mmBtu	128.0
Mississippi Power
Derivative [Line Items]
Net Purchased mmBtu	106.0
Southern Power
Derivative [Line Items]
Net Purchased mmBtu	8.0
Southern Company Gas
Derivative [Line Items]
Net Purchased mmBtu	63.0
Long | Not Designated as Hedging Instrument | Southern Company Gas
Derivative [Line Items]
Derivative nonmonetary notional amount net long short position volume	72.0
Short | Not Designated as Hedging Instrument | Southern Company Gas
Derivative [Line Items]
Derivative nonmonetary notional amount net long short position volume	9.0