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ASSET RETIREMENT OBLIGATIONS - Investment Securities in the Funds (Details) - USD ($)
$ in Millions
Dec. 31, 2024
Dec. 31, 2023
Marketable Securities [Line Items]    
Total investment securities in the Funds $ 2,621 $ 2,422
Equity securities    
Marketable Securities [Line Items]    
Total investment securities in the Funds 1,413 1,288
Debt securities    
Marketable Securities [Line Items]    
Total investment securities in the Funds 976 895
Other securities    
Marketable Securities [Line Items]    
Total investment securities in the Funds 232 239
Alabama Power    
Marketable Securities [Line Items]    
Total investment securities in the Funds 1,385 1,259
Alabama Power | Equity securities    
Marketable Securities [Line Items]    
Total investment securities in the Funds 848 796
Alabama Power | Debt securities    
Marketable Securities [Line Items]    
Total investment securities in the Funds 335 277
Alabama Power | Other securities    
Marketable Securities [Line Items]    
Total investment securities in the Funds 202 186
Georgia Power    
Marketable Securities [Line Items]    
Total investment securities in the Funds 1,236 1,163
Georgia Power | Equity securities    
Marketable Securities [Line Items]    
Total investment securities in the Funds 565 492
Georgia Power | Debt securities    
Marketable Securities [Line Items]    
Total investment securities in the Funds 641 618
Georgia Power | Other securities    
Marketable Securities [Line Items]    
Total investment securities in the Funds $ 30 $ 53