v3.26.1
Consolidated Entities and Equity Method Investments - Narrative (Details) - USD ($)
$ in Millions
 3 Months Ended 6 Months Ended
Jun. 30, 2026
Jun. 30, 2025
Jun. 30, 2026
Jun. 30, 2025
Dec. 31, 2025
Schedule of Equity Method Investments [Line Items]          
Equity investments in unconsolidated subsidiaries $ 1,428   $ 1,428   $ 1,318
Earnings from equity method investments 86 $ 10 136 $ 43  
Assets 162,027   162,027   155,720
Liabilities 119,685   119,685   116,853
Southern Holdings Company          
Schedule of Equity Method Investments [Line Items]          
Equity investments in unconsolidated subsidiaries 156   156   124
Earnings from equity method investments 45 (14) 48 (20)  
SOUTHERN POWER CO          
Schedule of Equity Method Investments [Line Items]          
Earnings from equity method investments     0 0  
Assets 12,780   12,780   12,657
Liabilities 6,038   6,038   6,136
SOUTHERN Co GAS          
Schedule of Equity Method Investments [Line Items]          
Equity investments in unconsolidated subsidiaries 1,254   1,254   1,182
Earnings from equity method investments 32 23 78 62  
Assets 27,604   27,604   27,387
Liabilities 16,163   16,163   16,260
SOUTHERN Co GAS | Other          
Schedule of Equity Method Investments [Line Items]          
Equity investments in unconsolidated subsidiaries 34   34   34
Earnings from equity method investments 0 $ 0 $ 0 $ 0  
SP Solar Holdings I, LP | SOUTHERN POWER CO          
Schedule of Equity Method Investments [Line Items]          
Distribution made to limited partner, cash distributions paid, percentage     67.00%    
SP Solar Holdings I, LP | Financial Investors          
Schedule of Equity Method Investments [Line Items]          
Distribution made to limited partner, cash distributions paid, percentage     33.00%    
Variable Interest Entity, Primary Beneficiary | SP Solar Holdings I, LP | SOUTHERN POWER CO          
Schedule of Equity Method Investments [Line Items]          
Assets 5,100   $ 5,100   5,200
Liabilities 364   364   360
Noncontrolling interests related to other partners' interests 907   907   918
Variable Interest Entity, Primary Beneficiary | Other Variable Interest Entities | SOUTHERN POWER CO          
Schedule of Equity Method Investments [Line Items]          
Assets 1,500   1,500   1,600
Liabilities 259   259   236
Noncontrolling interests related to other partners' interests $ 563   $ 563   $ 617