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ASSET RETIREMENT OBLIGATIONS - Investment Securities in the Funds (Details) - USD ($) $ in Millions | Dec. 31, 2024 | Dec. 31, 2023
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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

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