DERIVATIVES - Foreign Currency Derivatives (Details) € in Millions, $ in Millions	12 Months Ended
	Dec. 31, 2022 USD ($)	Dec. 31, 2022 EUR (€)	Dec. 31, 2021 USD ($)
Foreign currency derivatives | Cash Flow Hedges of Forecasted Debt
Derivative [Line Items]
Pay Notional	$ 2,040
Receive Notional | €		€ 1,750
Fair Value Gain (Loss) December 31, 2022	(216)
Southern Power
Derivative [Line Items]
Fair Value Gain (Loss) December 31, 2022	(31)		$ 5
Southern Power | Foreign currency derivatives | Cash Flow Hedges of Forecasted Debt
Derivative [Line Items]
Pay Notional	$ 564
Pay Rate	3.78%
Receive Notional | €		500
Receive Rate	1.85%
Southern Power | Foreign currency derivatives | April 2030 | Cash Flow Hedges of Forecasted Debt
Derivative [Line Items]
Fair Value Gain (Loss) December 31, 2022	$ (47)
Southern Company | Foreign currency derivatives | Cash Flow Hedges of Forecasted Debt
Derivative [Line Items]
Fair Value Gain (Loss) December 31, 2022	(169)
Southern Company | Foreign currency derivatives | April 2030 | Fair Value Hedges of Existing Debt
Derivative [Line Items]
Pay Notional	$ 1,476
Pay Rate	3.39%
Receive Notional | €		€ 1,250
Receive Rate	1.88%