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ASSET RETIREMENT OBLIGATIONS - Narrative (Details) - USD ($)
1 Months Ended 12 Months Ended
May 01, 2024
Aug. 01, 2023
Nov. 30, 2024
Sep. 30, 2024
Nov. 30, 2023
Sep. 30, 2023
Jun. 30, 2023
Dec. 31, 2024
Dec. 31, 2022
Dec. 31, 2019
Feb. 14, 2024
Dec. 31, 2023
Mar. 06, 2023
Jointly Owned Utility Plant Interests [Line Items]                          
Asset retirement obligations               $ 9,934,000,000 $ 10,840,000,000     $ 10,317,000,000  
Plant Vogtle Units 3 and 4                          
Jointly Owned Utility Plant Interests [Line Items]                          
Asset retirement obligations                         $ 90,000,000
Plant Vogtle Unit 4                          
Jointly Owned Utility Plant Interests [Line Items]                          
Asset retirement obligations                     $ 118,000,000    
Alabama Power                          
Jointly Owned Utility Plant Interests [Line Items]                          
Decrease to ARO             $ 15,000,000            
Asset retirement obligations               4,058,000,000 4,287,000,000     4,158,000,000  
Alabama Power | Internal reserves                          
Jointly Owned Utility Plant Interests [Line Items]                          
Accumulated provisions for decommissioning               $ 12,000,000       13,000,000  
Alabama Power | Plant Farley                          
Jointly Owned Utility Plant Interests [Line Items]                          
Estimated inflation rate               4.50%          
Estimated trust earnings rate               7.00%          
Alabama Power | Plant Farley                          
Jointly Owned Utility Plant Interests [Line Items]                          
Site-specific estimate of decommissioning costs, period of updates made               5 years          
Georgia Power                          
Jointly Owned Utility Plant Interests [Line Items]                          
Decrease to ARO     $ 60,000,000 $ 389,000,000 $ 210,000,000 $ 175,000,000              
Asset retirement obligations               $ 5,415,000,000 6,034,000,000     5,665,000,000  
Georgia Power | Plant Hatch                          
Jointly Owned Utility Plant Interests [Line Items]                          
Estimated inflation rate               2.50%          
Estimated trust earnings rate               4.50%          
Georgia Power | Plant Vogtle Units 3 and 4                          
Jointly Owned Utility Plant Interests [Line Items]                          
Estimated inflation rate               2.30%          
Estimated trust earnings rate               4.30%          
Georgia Power | Plant Hatch and Plant Vogtle Units 1 And 2                          
Jointly Owned Utility Plant Interests [Line Items]                          
Annual decommissioning cost for ratemaking                 0 $ 4,000,000      
Georgia Power | Plant Vogtle Units 3 and 4                          
Jointly Owned Utility Plant Interests [Line Items]                          
Annual decommissioning cost for ratemaking   $ 8,000,000                      
Georgia Power | Plant Vogtle Unit 4                          
Jointly Owned Utility Plant Interests [Line Items]                          
Annual decommissioning cost for ratemaking $ 8,000,000                        
Mississippi Power                          
Jointly Owned Utility Plant Interests [Line Items]                          
Asset retirement obligations               $ 148,000,000 $ 179,000,000     $ 168,000,000