FINANCING - Notes Payable (Details) - USD ($) $ in Millions	Dec. 31, 2022	Dec. 31, 2021
Short-term Debt [Line Items]
Amount Outstanding	$ 2,609	$ 1,440
Weighted Average Interest Rate	4.90%	0.40%
Commercial paper
Short-term Debt [Line Items]
Amount Outstanding	$ 809	$ 1,140
Weighted Average Interest Rate	4.70%	0.30%
Short-term bank debt
Short-term Debt [Line Items]
Amount Outstanding	$ 1,800	$ 300
Weighted Average Interest Rate	5.00%	0.70%
Georgia Power
Short-term Debt [Line Items]
Amount Outstanding	$ 1,600	$ 0
Georgia Power | Short-term bank debt
Short-term Debt [Line Items]
Amount Outstanding	$ 1,600	$ 0
Weighted Average Interest Rate	5.00%	0.00%
Southern Power
Short-term Debt [Line Items]
Amount Outstanding	$ 225	$ 211
Southern Power | Commercial paper
Short-term Debt [Line Items]
Amount Outstanding	$ 225	$ 211
Weighted Average Interest Rate	4.70%	0.30%
Southern Company Gas
Short-term Debt [Line Items]
Amount Outstanding	$ 768	$ 1,209
Southern Company Gas | Commercial paper
Short-term Debt [Line Items]
Amount Outstanding	$ 768	$ 1,209
Weighted Average Interest Rate	4.70%	0.40%
Southern Company Gas Capital | Commercial paper
Short-term Debt [Line Items]
Amount Outstanding	$ 285	$ 379
Weighted Average Interest Rate	4.80%	0.30%
Nicor Gas | Commercial paper
Short-term Debt [Line Items]
Amount Outstanding	$ 283	$ 530
Weighted Average Interest Rate	4.60%	0.30%
Nicor Gas | Short-term bank debt
Short-term Debt [Line Items]
Amount Outstanding	$ 200	$ 300
Weighted Average Interest Rate	4.90%	0.70%