v3.26.1
Introduction - Schedule of Other Intangible Assets (Details) - USD ($)
$ in Millions
Jun. 30, 2026
Dec. 31, 2025
Subject to amortization:    
Gross Carrying Amount $ 669 $ 669
Accumulated Amortization (457) (444)
Other Intangible Assets, Net 212 225
Not subject to amortization:    
FCC licenses 75 75
Total other intangible assets    
Gross Carrying Amount 744 744
Accumulated Amortization (457) (444)
Other Intangible Assets, Net 287 300
Customer relationships    
Subject to amortization:    
Gross Carrying Amount 212 212
Accumulated Amortization (192) (189)
Other Intangible Assets, Net 20 23
Total other intangible assets    
Accumulated Amortization (192) (189)
Trade names    
Subject to amortization:    
Gross Carrying Amount 64 64
Accumulated Amortization (64) (64)
Other Intangible Assets, Net 0 0
Total other intangible assets    
Accumulated Amortization (64) (64)
PPA fair value adjustments    
Subject to amortization:    
Gross Carrying Amount 390 390
Accumulated Amortization (198) (188)
Other Intangible Assets, Net 192 202
Total other intangible assets    
Accumulated Amortization (198) (188)
Other    
Subject to amortization:    
Gross Carrying Amount 3 3
Accumulated Amortization (3) (3)
Other Intangible Assets, Net 0 0
Total other intangible assets    
Accumulated Amortization (3) (3)
SOUTHERN POWER CO    
Subject to amortization:    
Accumulated Amortization (198) (188)
Total other intangible assets    
Accumulated Amortization (198) (188)
SOUTHERN POWER CO | PPA fair value adjustments    
Subject to amortization:    
Gross Carrying Amount 390 390
Accumulated Amortization (198) (188)
Other Intangible Assets, Net 192 202
Total other intangible assets    
Accumulated Amortization (198) (188)
SOUTHERN Co GAS    
Subject to amortization:    
Gross Carrying Amount 182 182
Accumulated Amortization (181) (179)
Other Intangible Assets, Net 1 3
Total other intangible assets    
Accumulated Amortization (181) (179)
Other Intangible Assets, Net 1 3
SOUTHERN Co GAS | Customer relationships    
Subject to amortization:    
Gross Carrying Amount 156 156
Accumulated Amortization (155) (153)
Other Intangible Assets, Net 1 3
Total other intangible assets    
Accumulated Amortization (155) (153)
SOUTHERN Co GAS | Trade names    
Subject to amortization:    
Gross Carrying Amount 26 26
Accumulated Amortization (26) (26)
Other Intangible Assets, Net 0 0
Total other intangible assets    
Accumulated Amortization $ (26) $ (26)