ASSET RETIREMENT OBLIGATIONS - Investment Securities in the Funds (Details) - USD ($) $ in Millions	Dec. 31, 2023	Dec. 31, 2022
Marketable Securities [Line Items]
Total investment securities in the Funds	$ 2,422	$ 2,143
Equity securities
Marketable Securities [Line Items]
Total investment securities in the Funds	1,288	1,095
Debt securities
Marketable Securities [Line Items]
Total investment securities in the Funds	895	838
Other securities
Marketable Securities [Line Items]
Total investment securities in the Funds	239	210
Alabama Power
Marketable Securities [Line Items]
Total investment securities in the Funds	1,259	1,125
Alabama Power | Equity securities
Marketable Securities [Line Items]
Total investment securities in the Funds	796	690
Alabama Power | Debt securities
Marketable Securities [Line Items]
Total investment securities in the Funds	277	267
Alabama Power | Other securities
Marketable Securities [Line Items]
Total investment securities in the Funds	186	168
Georgia Power
Marketable Securities [Line Items]
Total investment securities in the Funds	1,163	1,018
Fair market value of securities on loan and pledged to creditors		35
Fair value of collateral received		36
Georgia Power | Equity securities
Marketable Securities [Line Items]
Total investment securities in the Funds	492	405
Georgia Power | Debt securities
Marketable Securities [Line Items]
Total investment securities in the Funds	618	571
Georgia Power | Other securities
Marketable Securities [Line Items]
Total investment securities in the Funds	$ 53	$ 42