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CONSOLIDATED ENTITIES AND EQUITY METHOD INVESTMENTS - Balance Sheet Information (Details) - USD ($) $ in Millions | Dec. 31, 2024 | Dec. 31, 2023
--- | --- | ---
Schedule of Equity Method Investments [Line Items] |  |
Equity investments in unconsolidated subsidiaries | $ 1,416 | $ 1,368
Southern Company Gas |  |
Schedule of Equity Method Investments [Line Items] |  |
Equity investments in unconsolidated subsidiaries | 1,279 | 1,235
SNG | Southern Company Gas |  |
Schedule of Equity Method Investments [Line Items] |  |
Equity investments in unconsolidated subsidiaries | 1,245 | 1,202
Other | Southern Company Gas |  |
Schedule of Equity Method Investments [Line Items] |  |
Equity investments in unconsolidated subsidiaries | $ 34 | $ 33

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