Consolidated Entities and Equity Method Investments - Schedule of Equity Method Investments (Details) - USD ($) $ in Millions	Mar. 31, 2024	Dec. 31, 2023
Schedule of Equity Method Investments [Line Items]
Investment Balance	$ 1,395	$ 1,368
SOUTHERN Co GAS
Schedule of Equity Method Investments [Line Items]
Investment Balance	1,260	1,235
SOUTHERN Co GAS | SNG
Schedule of Equity Method Investments [Line Items]
Investment Balance	1,227	1,202
SOUTHERN Co GAS | Other
Schedule of Equity Method Investments [Line Items]
Investment Balance	$ 33	$ 33