v3.25.0.1
RETIREMENT BENEFITS - Amounts Recognized in Balance Sheets and Amounts in AOCI (Details) - USD ($)
$ in Millions
Dec. 31, 2024
Dec. 31, 2023
Dec. 31, 2022
Defined Benefit Plan Disclosure [Line Items]      
Other regulatory assets, deferred $ 7,037 $ 6,264  
Other current liabilities (1,100) (1,029)  
Employee benefit obligations (1,011) (1,115)  
Other regulatory liabilities, deferred (692) (715)  
Regulatory asset   66 $ 216
Other deferred charges and assets 1,467 1,468  
Pension plans      
Defined Benefit Plan Disclosure [Line Items]      
Prepaid pension costs 2,674 2,079  
Other regulatory assets, deferred 2,708 2,960  
Other current liabilities (68) (64)  
Employee benefit obligations (611) (649)  
Other regulatory liabilities, deferred (50) (47)  
AOCI 52 79  
Other Postretirement Benefits Plan      
Defined Benefit Plan Disclosure [Line Items]      
Other regulatory assets, deferred 24 23  
Other current liabilities (6) (6)  
Employee benefit obligations (212) (285)  
Other regulatory liabilities, deferred (213) (231)  
AOCI (14) (9)  
Prepaid pension and other postretirement benefit costs 0 0  
Alabama Power      
Defined Benefit Plan Disclosure [Line Items]      
Other regulatory assets, deferred 1,815 1,858  
Other current liabilities (219) (191)  
Employee benefit obligations (148) (155)  
Other regulatory liabilities, deferred (271) (291)  
Regulatory asset 70 76 97
Prepaid pension and other postretirement benefit costs 841 659  
Other deferred charges and assets 391 414  
Alabama Power | Pension plans      
Defined Benefit Plan Disclosure [Line Items]      
Prepaid pension costs 746 585  
Other regulatory assets, deferred 741 821  
Other current liabilities (13) (11)  
Employee benefit obligations (102) (106)  
Other regulatory liabilities, deferred 0 0  
AOCI 0 0  
Alabama Power | Other Postretirement Benefits Plan      
Defined Benefit Plan Disclosure [Line Items]      
Other regulatory assets, deferred 0 0  
Other current liabilities 0 0  
Employee benefit obligations 0 0  
Other regulatory liabilities, deferred (45) (48)  
AOCI 0 0  
Prepaid pension and other postretirement benefit costs 95 74  
Georgia Power      
Defined Benefit Plan Disclosure [Line Items]      
Other regulatory assets, deferred 3,814 2,890  
Other current liabilities (296) (365)  
Employee benefit obligations (205) (248)  
Regulatory asset     83
Other deferred charges and assets 615 508  
Georgia Power | Pension plans      
Defined Benefit Plan Disclosure [Line Items]      
Prepaid pension costs 897 706  
Other regulatory assets, deferred 973 1,051  
Other current liabilities (13) (13)  
Employee benefit obligations (98) (131)  
Other regulatory liabilities, deferred 0 0  
AOCI 0 0  
Georgia Power | Other Postretirement Benefits Plan      
Defined Benefit Plan Disclosure [Line Items]      
Other regulatory assets, deferred 3 11  
Other current liabilities 0 0  
Employee benefit obligations (68) (79)  
Other regulatory liabilities, deferred (67) (85)  
AOCI 0 0  
Prepaid pension and other postretirement benefit costs 0 0  
Mississippi Power      
Defined Benefit Plan Disclosure [Line Items]      
Other regulatory assets, deferred 259 285  
Other current liabilities (95) (90)  
Employee benefit obligations (65) (67)  
Other regulatory liabilities, deferred (121) (92)  
Regulatory asset 52 44 $ 36
Other deferred charges and assets 74 85  
Mississippi Power | Pension plans      
Defined Benefit Plan Disclosure [Line Items]      
Prepaid pension costs 124 99  
Other regulatory assets, deferred 144 152  
Other current liabilities (2) (2)  
Employee benefit obligations (25) (27)  
Other regulatory liabilities, deferred 0 0  
AOCI 0 0  
Mississippi Power | Other Postretirement Benefits Plan      
Defined Benefit Plan Disclosure [Line Items]      
Other regulatory assets, deferred 0 0  
Other current liabilities 0 0  
Employee benefit obligations (31) (32)  
Other regulatory liabilities, deferred (9) (10)  
AOCI 0 0  
Prepaid pension and other postretirement benefit costs 0 0  
Southern Power      
Defined Benefit Plan Disclosure [Line Items]      
Other current liabilities (96) (97)  
Other deferred charges and assets 232 262  
Southern Power | Pension plans      
Defined Benefit Plan Disclosure [Line Items]      
Prepaid pension costs 41 31  
Other regulatory assets, deferred 0 0  
Other current liabilities (2) (2)  
Employee benefit obligations (18) (21)  
Other regulatory liabilities, deferred 0 0  
AOCI 11 20  
Southern Power | Other Postretirement Benefits Plan      
Defined Benefit Plan Disclosure [Line Items]      
Other regulatory assets, deferred 0 0  
Other current liabilities (1) (1)  
Employee benefit obligations (8) (8)  
Other regulatory liabilities, deferred 0 0  
AOCI 0 1  
Prepaid pension and other postretirement benefit costs 0 0  
Southern Company Gas      
Defined Benefit Plan Disclosure [Line Items]      
Other regulatory assets, deferred 481 504  
Other current liabilities (237) (232)  
Employee benefit obligations (78) (110)  
Other deferred charges and assets 192 181  
Southern Company Gas | Pension plans      
Defined Benefit Plan Disclosure [Line Items]      
Prepaid pension costs 191 158  
Other regulatory assets, deferred 126 143  
Other current liabilities (4) (3)  
Employee benefit obligations (51) (58)  
Other regulatory liabilities, deferred 0 0  
AOCI (54) (45)  
Regulatory asset 155 173  
Southern Company Gas | Other Postretirement Benefits Plan      
Defined Benefit Plan Disclosure [Line Items]      
Other regulatory assets, deferred 0 0  
Other current liabilities 0 0  
Employee benefit obligations (15) (44)  
Other regulatory liabilities, deferred (84) (68)  
AOCI (15) (10)  
Regulatory asset 16 24  
Prepaid pension and other postretirement benefit costs $ 0 $ 0