DERIVATIVES - Interest Rate Derivatives (Details) - Interest rate derivatives $ in Millions	12 Months Ended
	Dec. 31, 2022 USD ($)
Derivative [Line Items]
Notional Amount	$ 2,300
Fair Value Gain (Loss) December 31, 2022	(290)
Southern Company | Cash Flow Hedges of Forecasted Debt
Derivative [Line Items]
Notional Amount	$ 400
Weighted Average Interest Rate Paid	3.50%
Fair Value Gain (Loss) December 31, 2022	$ 12
Southern Company | Fair Value Hedges of Existing Debt | March 2028
Derivative [Line Items]
Notional Amount	$ 400
Weighted Average Interest Rate Paid	0.68%
Interest Rate Received	1.75%
Fair Value Gain (Loss) December 31, 2022	$ (55)
Southern Company | Fair Value Hedges of Existing Debt | April 2030
Derivative [Line Items]
Notional Amount	$ 1,000
Weighted Average Interest Rate Paid	2.36%
Interest Rate Received	3.70%
Fair Value Gain (Loss) December 31, 2022	$ (161)
Southern Company Gas [Member] | Fair Value Hedges of Existing Debt
Derivative [Line Items]
Notional Amount	$ 500
Weighted Average Interest Rate Paid	0.38%
Interest Rate Received	1.75%
Fair Value Gain (Loss) December 31, 2022	$ (86)