PROPERTY, PLANT, AND EQUIPMENT - Deferred Cloud Implementation Costs (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021
Property, Plant and Equipment [Line Items]
Deferred cloud implementation costs	$ 20,148	$ 17,259
Deferred Cloud Implementation Costs
Property, Plant and Equipment [Line Items]
Deferred cloud implementation costs	345	240
Amortization	29	0
Alabama Power
Property, Plant and Equipment [Line Items]
Deferred cloud implementation costs	5,372	4,549
Alabama Power | Deferred Cloud Implementation Costs
Property, Plant and Equipment [Line Items]
Deferred cloud implementation costs	81	54
Amortization	8	0
Georgia Power
Property, Plant and Equipment [Line Items]
Deferred cloud implementation costs	11,117	8,823
Georgia Power | Deferred Cloud Implementation Costs
Property, Plant and Equipment [Line Items]
Deferred cloud implementation costs	108	81
Amortization	12	0
Mississippi Power
Property, Plant and Equipment [Line Items]
Deferred cloud implementation costs	828	877
Mississippi Power | Deferred Cloud Implementation Costs
Property, Plant and Equipment [Line Items]
Deferred cloud implementation costs	14	11
Amortization	0	0
Southern Power
Property, Plant and Equipment [Line Items]
Deferred cloud implementation costs	956	967
Southern Power | Deferred Cloud Implementation Costs
Property, Plant and Equipment [Line Items]
Deferred cloud implementation costs	18	14
Amortization	0	0
Southern Company Gas
Property, Plant and Equipment [Line Items]
Deferred cloud implementation costs	882	1,064
Southern Company Gas | Deferred Cloud Implementation Costs
Property, Plant and Equipment [Line Items]
Deferred cloud implementation costs	54	35
Amortization	$ 0	$ 0