ASSET RETIREMENT OBLIGATIONS - Investment Securities in the Funds (Details) - USD ($) $ in Millions	Dec. 31, 2022	Dec. 31, 2021
Marketable Securities [Line Items]
Total investment securities in the Funds	$ 2,143	$ 2,541
Equity securities
Marketable Securities [Line Items]
Total investment securities in the Funds	1,095	1,358
Debt securities
Marketable Securities [Line Items]
Total investment securities in the Funds	838	986
Other securities
Marketable Securities [Line Items]
Total investment securities in the Funds	210	197
Alabama Power
Marketable Securities [Line Items]
Total investment securities in the Funds	1,125	1,324
Alabama Power | Equity securities
Marketable Securities [Line Items]
Total investment securities in the Funds	690	849
Alabama Power | Debt securities
Marketable Securities [Line Items]
Total investment securities in the Funds	267	316
Alabama Power | Other securities
Marketable Securities [Line Items]
Total investment securities in the Funds	168	159
Georgia Power
Marketable Securities [Line Items]
Total investment securities in the Funds	1,018	1,217
Georgia Power | Equity securities
Marketable Securities [Line Items]
Total investment securities in the Funds	405	509
Georgia Power | Debt securities
Marketable Securities [Line Items]
Total investment securities in the Funds	571	670
Georgia Power | Other securities
Marketable Securities [Line Items]
Total investment securities in the Funds	$ 42	$ 38