Derivatives - Schedule of Interest Rate Derivatives (Details) - Interest rate derivatives $ in Millions	6 Months Ended
	Jun. 30, 2025 USD ($)
Derivative [Line Items]
Notional Amount	$ 2,990
Fair Value Gain (Loss)	(197)
GEORGIA POWER CO | Cash Flow Hedges of Forecasted Debt | Date One
Derivative [Line Items]
Notional Amount	$ 275
Weighted Average Interest Rate Paid	4.29%
Fair Value Gain (Loss)	$ (1)
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)	$ (30)
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)	$ (106)
Southern Company parent | Fair Value Hedges of Existing Debt | Date Three
Derivative [Line Items]
Notional Amount	$ 565
Weighted Average Interest Rate Paid	1.56%
Interest Rate Received	6.50%
Fair Value Gain (Loss)	$ (1)
SOUTHERN Co GAS | Cash Flow Hedges of Forecasted Debt | Date One
Derivative [Line Items]
Notional Amount	$ 250
Weighted Average Interest Rate Paid	4.03%
Fair Value Gain (Loss)	$ 4
SOUTHERN Co GAS | Fair Value Hedges of Existing Debt
Derivative [Line Items]
Fair Value Gain (Loss)	(63)
SOUTHERN Co GAS | Fair Value Hedges of Existing Debt | Date One
Derivative [Line Items]
Notional Amount	$ 500
Weighted Average Interest Rate Paid	0.49%
Interest Rate Received	1.75%