v3.26.1
Segment and Related Information - Schedule of Gas Revenues (Details) - USD ($)
$ in Millions
 3 Months Ended 6 Months Ended
Jun. 30, 2026
Mar. 31, 2026
Jun. 30, 2025
Mar. 31, 2025
Jun. 30, 2026
Jun. 30, 2025
Dec. 31, 2025
Segment Reporting [Line Items]              
Total operating revenues $ 6,977   $ 6,973   $ 15,374 $ 14,748  
Other segment items 3,472   3,617   8,138 7,812  
Depreciation and amortization(b) 1,434   1,323   2,854 2,608  
Interest expense(d) 796   874   1,573 1,588  
Income taxes (benefit) 187   289   414 569  
Consolidated Net Income Attributable to Southern Company 1,174   880   2,531 2,214  
Total assets 162,027       162,027   $ 155,720
Earnings from equity method investments 86   10   136 43  
SOUTHERN Co GAS              
Segment Reporting [Line Items]              
Total operating revenues 966   979   3,157 2,818  
Other segment items 554   599   1,911 1,670  
Depreciation and amortization(b) 185   172   369 341  
Interest expense(d) 101   92   206 183  
Income taxes (benefit) 32   33   176 162  
Consolidated Net Income Attributable to Southern Company 126 $ 447 106 $ 418 573 524  
Total assets 27,604       27,604   27,387
Earnings from equity method investments 32   23   78 62  
Operating Segments              
Segment Reporting [Line Items]              
Total operating revenues 6,792   6,783   15,005 14,378  
Other segment items 3,306   3,447   7,824 7,492  
Depreciation and amortization(b) 1,417   1,306   2,820 2,575  
Interest expense(d) 484   452   954 885  
Income taxes (benefit) 259   401   563 755  
Consolidated Net Income Attributable to Southern Company 1,370   1,204   2,933 2,735  
Total assets 158,477       158,477   153,416
Earnings from equity method investments 44   27   89 64  
Operating Segments | SOUTHERN Co GAS              
Segment Reporting [Line Items]              
Total operating revenues 966   976   3,159 2,815  
Other segment items 551   595   1,911 1,668  
Depreciation and amortization(b) 185   171   367 340  
Interest expense(d) 100   92   201 183  
Income taxes (benefit) 34   27   189 165  
Consolidated Net Income Attributable to Southern Company 128   114   569 521  
Total assets 29,500       29,500   28,615
Earnings from equity method investments 32   23   78 62  
Operating Segments | Gas distribution operations | SOUTHERN Co GAS              
Segment Reporting [Line Items]              
Total operating revenues 885   885   2,785 2,454  
Other segment items 496   526   1,673 1,431  
Depreciation and amortization(b) 181   167   360 330  
Interest expense(d) 90   82   181 164  
Income taxes (benefit) 23   19   139 123  
Consolidated Net Income Attributable to Southern Company 95   91   432 406  
Total assets 26,244       26,244   25,391
Earnings from equity method investments 0   0   0 0  
Operating Segments | Gas Pipeline Investments | SOUTHERN Co GAS              
Segment Reporting [Line Items]              
Total operating revenues 8   8   16 16  
Other segment items 1   1   1 3  
Depreciation and amortization(b) 1   1   2 3  
Interest expense(d) 9   9   18 18  
Income taxes (benefit) 7   5   18 13  
Consolidated Net Income Attributable to Southern Company 22   15   55 41  
Total assets 1,546       1,546   1,475
Earnings from equity method investments 32   23   78 62  
Operating Segments | Gas marketing services | SOUTHERN Co GAS              
Segment Reporting [Line Items]              
Total operating revenues 73   83   358 345  
Other segment items 54   68   237 234  
Depreciation and amortization(b) 3   3   5 7  
Interest expense(d) 1   1   2 1  
Income taxes (benefit) 4   3   32 29  
Consolidated Net Income Attributable to Southern Company 11   8   82 74  
Total assets 1,710       1,710   1,749
Earnings from equity method investments 0   0   0 0  
All Other              
Segment Reporting [Line Items]              
Total operating revenues 223   225   441 454  
Other segment items 193   193   382 401  
Depreciation and amortization(b) 17   17   34 33  
Interest expense(d) 312   422   619 703  
Income taxes (benefit) (72)   (112)   (149) (186)  
Consolidated Net Income Attributable to Southern Company (185)   (312)   (398) (518)  
Total assets 4,283       4,283   2,829
Earnings from equity method investments 42   (17)   47 (21)  
All Other | SOUTHERN Co GAS              
Segment Reporting [Line Items]              
Total operating revenues 2   5   4 9  
Other segment items 5   6   6 8  
Depreciation and amortization(b) 0   1   2 1  
Interest expense(d) 1   0   5 0  
Income taxes (benefit) (2)   6   (13) (3)  
Consolidated Net Income Attributable to Southern Company (2)   (8)   4 3  
Total assets 11,265       11,265   10,643
Earnings from equity method investments 0   0   0 0  
Eliminations              
Segment Reporting [Line Items]              
Total operating revenues (38)   (35)   (72) (84)  
Other segment items (27)   (23)   (68) (81)  
Depreciation and amortization(b) 0   0   0 0  
Interest expense(d) 0   0   0 0  
Income taxes (benefit) 0   0   0 0  
Consolidated Net Income Attributable to Southern Company (11)   (12)   (4) (3)  
Total assets (733)       (733)   (525)
Earnings from equity method investments 0   0   0 0  
Eliminations | SOUTHERN Co GAS              
Segment Reporting [Line Items]              
Total operating revenues (2)   (2)   (6) (6)  
Other segment items (2)   (2)   (6) (6)  
Depreciation and amortization(b) 0   0   0 0  
Interest expense(d) 0   0   0 0  
Income taxes (benefit) 0   0   0 0  
Consolidated Net Income Attributable to Southern Company 0   0   0 0  
Total assets (13,161)       (13,161)   $ (11,871)
Earnings from equity method investments $ 0   $ 0   $ 0 $ 0