Derivatives - Schedule of Interest Rate Derivatives (Details) - Interest rate derivatives $ in Millions	3 Months Ended
	Mar. 31, 2022 USD ($)
Derivative [Line Items]
Notional Amount	$ 2,300
Fair Value Gain (Loss)	(122)
GEORGIA POWER CO | Cash Flow Hedges of Forecasted Debt | February 2032
Derivative [Line Items]
Notional Amount	$ 200
Interest Rate Received	1.87%
Weighted Average Interest Rate Paid	0.00%
Fair Value Gain (Loss)	$ 8
GEORGIA POWER CO | Cash Flow Hedges of Forecasted Debt | November 2051
Derivative [Line Items]
Notional Amount	$ 100
Interest Rate Received	2.27%
Weighted Average Interest Rate Paid	0.00%
Fair Value Gain (Loss)	$ 4
Southern Company parent | Cash Flow Hedges of Existing Debt
Derivative [Line Items]
Notional Amount	$ 100
Interest Rate Received	2.58%
Weighted Average Interest Rate Paid	0.00%
Fair Value Gain (Loss)	$ (1)
Southern Company parent | Fair Value Hedges of Existing Debt | March 2028
Derivative [Line Items]
Notional Amount	$ 400
Interest Rate Received	1.75%
Fair Value Gain (Loss)	$ (29)
Southern Company parent | Fair Value Hedges of Existing Debt | April 2030
Derivative [Line Items]
Notional Amount	$ 1,000
Interest Rate Received	3.70%
Fair Value Gain (Loss)	$ (69)
SOUTHERN Co GAS | Fair Value Hedges of Existing Debt
Derivative [Line Items]
Notional Amount	$ 500
Interest Rate Received	1.75%
Fair Value Gain (Loss)	$ (35)
London Interbank Offered Rate (LIBOR) | Southern Company parent | Fair Value Hedges of Existing Debt | March 2028
Derivative [Line Items]
Weighted Average Interest Rate Paid	0.68%
London Interbank Offered Rate (LIBOR) | Southern Company parent | Fair Value Hedges of Existing Debt | April 2030
Derivative [Line Items]
Weighted Average Interest Rate Paid	2.36%
London Interbank Offered Rate (LIBOR) | SOUTHERN Co GAS | Fair Value Hedges of Existing Debt
Derivative [Line Items]
Weighted Average Interest Rate Paid	0.38%