DERIVATIVES - Foreign Currency Derivatives (Details) € in Millions, $ in Millions	12 Months Ended
	Dec. 31, 2024 USD ($)	Dec. 31, 2024 EUR (€)	Dec. 31, 2023 USD ($)
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, 2024	(218)
Southern Power
Derivative [Line Items]
Fair Value Gain (Loss) December 31, 2024	(45)		$ (12)
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 \| Date \| Cash Flow Hedges of Forecasted Debt
Derivative [Line Items]
Fair Value Gain (Loss) December 31, 2024	$ (51)
Southern Company \| Foreign currency derivatives \| Cash Flow Hedges of Forecasted Debt
Derivative [Line Items]
Fair Value Gain (Loss) December 31, 2024	(167)
Southern Company \| Foreign currency derivatives \| Date \| 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%