Consolidated Entities and Equity Method Investments - Schedule of Earnings (Loss) from Equity Method Investments (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2024	Mar. 31, 2023
Schedule of Equity Method Investments [Line Items]
Earnings from Equity Method Investments	$ 45	$ 48
SOUTHERN Co GAS
Schedule of Equity Method Investments [Line Items]
Earnings from Equity Method Investments	44	45
SOUTHERN Co GAS | SNG
Schedule of Equity Method Investments [Line Items]
Earnings from Equity Method Investments	44	44
SOUTHERN Co GAS | Other
Schedule of Equity Method Investments [Line Items]
Earnings from Equity Method Investments	$ 0	$ 1