v3.26.1
Fair Value Measurements - Schedule of Increase (Decrease) In Fair Value Of Funds (Details) - USD ($)
$ in Millions
3 Months Ended 6 Months Ended
Jun. 30, 2026
Jun. 30, 2025
Jun. 30, 2026
Jun. 30, 2025
Fair Value, Option, Quantitative Disclosures [Line Items]        
Increase (decrease) in fair value of funds $ 249 $ 165 $ 205 $ 159
ALABAMA POWER CO        
Fair Value, Option, Quantitative Disclosures [Line Items]        
Increase (decrease) in fair value of funds 156 99 126 86
GEORGIA POWER CO        
Fair Value, Option, Quantitative Disclosures [Line Items]        
Increase (decrease) in fair value of funds $ 93 $ 66 $ 79 $ 73