Derivatives - Schedule of Interest Rate Derivatives (Details) - Interest rate derivatives $ in Millions	6 Months Ended
	Jun. 30, 2024 USD ($)
Derivative [Line Items]
Notional Amount	$ 2,000
Fair Value Gain (Loss)	(295)
Southern Company parent | Fair Value Hedges of Existing Debt | Date One
Derivative [Line Items]
Notional Amount	$ 400
Weighted Average Interest Rate Paid	0.80%
Interest Rate Received	1.75%
Fair Value Gain (Loss)	$ (50)
Southern Company parent | Fair Value Hedges of Existing Debt | Date Two
Derivative [Line Items]
Notional Amount	$ 1,000
Weighted Average Interest Rate Paid	2.48%
Interest Rate Received	3.70%
Fair Value Gain (Loss)	$ (157)
SOUTHERN Co GAS | Cash Flow Hedges of Forecasted Debt | Date One
Derivative [Line Items]
Notional Amount	$ 100
Weighted Average Interest Rate Paid	4.30%
Fair Value Gain (Loss)	$ 1
SOUTHERN Co GAS | Fair Value Hedges of Existing Debt
Derivative [Line Items]
Fair Value Gain (Loss)	(89)
SOUTHERN Co GAS | Fair Value Hedges of Existing Debt | Date Three
Derivative [Line Items]
Notional Amount	$ 500
Weighted Average Interest Rate Paid	0.49%
Interest Rate Received	1.75%