v3.25.0.1
RETIREMENT BENEFITS - Projected Benefit Plan Obligations (Details) - Pension plans - USD ($)
$ in Millions
Dec. 31, 2024
Dec. 31, 2023
Dec. 31, 2022
Defined Benefit Plan Disclosure [Line Items]      
Projected benefit obligations: $ 12,564 $ 13,252 $ 12,602
Alabama Power      
Defined Benefit Plan Disclosure [Line Items]      
Projected benefit obligations: 2,908 3,076 2,906
Georgia Power      
Defined Benefit Plan Disclosure [Line Items]      
Projected benefit obligations: 3,733 4,009 3,851
Mississippi Power      
Defined Benefit Plan Disclosure [Line Items]      
Projected benefit obligations: 567 599 569
SOUTHERN POWER CO      
Defined Benefit Plan Disclosure [Line Items]      
Projected benefit obligations: 167 177 163
Southern Company Gas      
Defined Benefit Plan Disclosure [Line Items]      
Projected benefit obligations: 842 $ 882 $ 868
Qualified pension plan      
Defined Benefit Plan Disclosure [Line Items]      
Projected benefit obligations: 11,886    
Qualified pension plan | Alabama Power      
Defined Benefit Plan Disclosure [Line Items]      
Projected benefit obligations: 2,794    
Qualified pension plan | Georgia Power      
Defined Benefit Plan Disclosure [Line Items]      
Projected benefit obligations: 3,622    
Qualified pension plan | Mississippi Power      
Defined Benefit Plan Disclosure [Line Items]      
Projected benefit obligations: 540    
Qualified pension plan | SOUTHERN POWER CO      
Defined Benefit Plan Disclosure [Line Items]      
Projected benefit obligations: 146    
Qualified pension plan | Southern Company Gas      
Defined Benefit Plan Disclosure [Line Items]      
Projected benefit obligations: 788    
Non-qualified pension plan      
Defined Benefit Plan Disclosure [Line Items]      
Projected benefit obligations: 678    
Non-qualified pension plan | Alabama Power      
Defined Benefit Plan Disclosure [Line Items]      
Projected benefit obligations: 114    
Non-qualified pension plan | Georgia Power      
Defined Benefit Plan Disclosure [Line Items]      
Projected benefit obligations: 111    
Non-qualified pension plan | Mississippi Power      
Defined Benefit Plan Disclosure [Line Items]      
Projected benefit obligations: 27    
Non-qualified pension plan | SOUTHERN POWER CO      
Defined Benefit Plan Disclosure [Line Items]      
Projected benefit obligations: 21    
Non-qualified pension plan | Southern Company Gas      
Defined Benefit Plan Disclosure [Line Items]      
Projected benefit obligations: $ 54