INCOME TAXES - Deferred Tax Assets and Liabilities (Details) - USD ($) $ in Millions	Dec. 31, 2023	Dec. 31, 2022
Deferred tax liabilities —
Deferred income tax liabilities	$ 18,574	$ 18,066
Deferred tax assets —
Deferred income tax assets	7,886	8,398
Valuation allowance	(206)	(257)
Net deferred income tax assets	7,680	8,141
Net deferred income taxes liabilities	10,894	9,925
Accumulated deferred income taxes – assets	(96)	(111)
Accumulated deferred income taxes – liabilities	10,990	10,036
Accelerated depreciation
Deferred tax liabilities —
Deferred income tax liabilities	9,683	9,443
Property basis differences
Deferred tax liabilities —
Deferred income tax liabilities	2,647	2,350
Employee benefit obligations
Deferred tax liabilities —
Deferred income tax liabilities	979	888
Deferred tax assets —
Deferred income tax assets	985	890
AROs
Deferred tax liabilities —
Deferred income tax liabilities	833	876
Under recovered fuel and natural gas costs
Deferred tax liabilities —
Deferred income tax liabilities	601	805
AROs
Deferred tax liabilities —
Deferred income tax liabilities	1,902	2,006
Employee benefit obligations
Deferred tax liabilities —
Deferred income tax liabilities	797	677
Remaining book value of retired assets
Deferred tax liabilities —
Deferred income tax liabilities	369	400
Premium on reacquired debt
Deferred tax liabilities —
Deferred income tax liabilities	63	66
Other
Deferred tax liabilities —
Deferred income tax liabilities	700	555
ITC and PTC carryforwards
Deferred tax assets —
Deferred income tax assets	1,387	1,685
Estimated loss on plants under construction
Deferred tax assets —
Deferred income tax assets	857	888
Estimated loss on regulatory disallowance
Deferred tax assets —
Deferred income tax assets	26
Other state deferred tax attributes
Deferred tax assets —
Deferred income tax assets	363	388
Federal effect of net state deferred tax assets/liabilities
Deferred tax assets —
Deferred income tax assets	418	365
Other property basis differences
Deferred tax assets —
Deferred income tax assets	197	207
State effect of federal deferred taxes
Deferred tax assets —
Deferred income tax assets	115	136
Other partnership basis differences
Deferred tax assets —
Deferred income tax assets	85	111
Regulatory liability associated with the Tax Reform Legislation (not subject to normalization)
Deferred tax assets —
Deferred income tax assets	34	137
Long-term debt fair value adjustment
Deferred tax assets —
Deferred income tax assets	79	85
Other comprehensive losses
Deferred tax assets —
Deferred income tax assets	67	72
Other
Deferred tax assets —
Deferred income tax assets	538	552
AROs
Deferred tax assets —
Deferred income tax assets	2,735	2,882
Alabama Power
Deferred tax liabilities —
Deferred income tax liabilities	6,101	6,024
Deferred tax assets —
Deferred income tax assets	1,931	2,043
Valuation allowance	0	0
Net deferred income tax assets	1,931	2,043
Net deferred income taxes liabilities	4,170	3,981
Accumulated deferred income taxes – assets	0	0
Accumulated deferred income taxes – liabilities	4,170	3,981
Alabama Power | Accelerated depreciation
Deferred tax liabilities —
Deferred income tax liabilities	2,566	2,564
Alabama Power | Property basis differences
Deferred tax liabilities —
Deferred income tax liabilities	1,444	1,303
Alabama Power | Employee benefit obligations
Deferred tax liabilities —
Deferred income tax liabilities	321	284
Deferred tax assets —
Deferred income tax assets	224	198
Alabama Power | AROs
Deferred tax liabilities —
Deferred income tax liabilities	476	499
Alabama Power | Under recovered fuel and natural gas costs
Deferred tax liabilities —
Deferred income tax liabilities	80	185
Alabama Power | AROs
Deferred tax liabilities —
Deferred income tax liabilities	667	679
Alabama Power | Employee benefit obligations
Deferred tax liabilities —
Deferred income tax liabilities	213	180
Alabama Power | Remaining book value of retired assets
Deferred tax liabilities —
Deferred income tax liabilities	143	142
Alabama Power | Premium on reacquired debt
Deferred tax liabilities —
Deferred income tax liabilities	9	9
Alabama Power | Other
Deferred tax liabilities —
Deferred income tax liabilities	182	179
Alabama Power | ITC and PTC carryforwards
Deferred tax assets —
Deferred income tax assets	12	12
Alabama Power | Estimated loss on plants under construction
Deferred tax assets —
Deferred income tax assets	0	0
Alabama Power | Estimated loss on regulatory disallowance
Deferred tax assets —
Deferred income tax assets	0
Alabama Power | Other state deferred tax attributes
Deferred tax assets —
Deferred income tax assets	0	0
Alabama Power | Federal effect of net state deferred tax assets/liabilities
Deferred tax assets —
Deferred income tax assets	215	175
Alabama Power | Other property basis differences
Deferred tax assets —
Deferred income tax assets	0	0
Alabama Power | State effect of federal deferred taxes
Deferred tax assets —
Deferred income tax assets	115	136
Alabama Power | Other partnership basis differences
Deferred tax assets —
Deferred income tax assets	0	0
Alabama Power | Regulatory liability associated with the Tax Reform Legislation (not subject to normalization)
Deferred tax assets —
Deferred income tax assets	30	127
Alabama Power | Long-term debt fair value adjustment
Deferred tax assets —
Deferred income tax assets	0	0
Alabama Power | Other comprehensive losses
Deferred tax assets —
Deferred income tax assets	4	4
Alabama Power | Other
Deferred tax assets —
Deferred income tax assets	188	213
Alabama Power | AROs
Deferred tax assets —
Deferred income tax assets	1,143	1,178
Georgia Power
Deferred tax liabilities —
Deferred income tax liabilities	7,661	7,426
Deferred tax assets —
Deferred income tax assets	3,718	3,844
Valuation allowance	(75)	(125)
Net deferred income tax assets	3,643	3,719
Net deferred income taxes liabilities	4,018	3,707
Accumulated deferred income taxes – assets	0	0
Accumulated deferred income taxes – liabilities	4,018	3,707
Georgia Power | Accelerated depreciation
Deferred tax liabilities —
Deferred income tax liabilities	3,628	3,447
Georgia Power | Property basis differences
Deferred tax liabilities —
Deferred income tax liabilities	812	693
Georgia Power | Employee benefit obligations
Deferred tax liabilities —
Deferred income tax liabilities	446	412
Deferred tax assets —
Deferred income tax assets	316	304
Georgia Power | AROs
Deferred tax liabilities —
Deferred income tax liabilities	314	324
Georgia Power | Under recovered fuel and natural gas costs
Deferred tax liabilities —
Deferred income tax liabilities	508	548
Georgia Power | AROs
Deferred tax liabilities —
Deferred income tax liabilities	1,196	1,285
Georgia Power | Employee benefit obligations
Deferred tax liabilities —
Deferred income tax liabilities	260	226
Georgia Power | Remaining book value of retired assets
Deferred tax liabilities —
Deferred income tax liabilities	221	253
Georgia Power | Premium on reacquired debt
Deferred tax liabilities —
Deferred income tax liabilities	53	57
Georgia Power | Other
Deferred tax liabilities —
Deferred income tax liabilities	223	181
Georgia Power | ITC and PTC carryforwards
Deferred tax assets —
Deferred income tax assets	691	673
Georgia Power | Estimated loss on plants under construction
Deferred tax assets —
Deferred income tax assets	857	888
Georgia Power | Estimated loss on regulatory disallowance
Deferred tax assets —
Deferred income tax assets	0
Georgia Power | Other state deferred tax attributes
Deferred tax assets —
Deferred income tax assets	13	12
Georgia Power | Federal effect of net state deferred tax assets/liabilities
Deferred tax assets —
Deferred income tax assets	92	88
Georgia Power | Other property basis differences
Deferred tax assets —
Deferred income tax assets	83	79
Georgia Power | State effect of federal deferred taxes
Deferred tax assets —
Deferred income tax assets	0	0
Georgia Power | Other partnership basis differences
Deferred tax assets —
Deferred income tax assets	0	0
Georgia Power | Regulatory liability associated with the Tax Reform Legislation (not subject to normalization)
Deferred tax assets —
Deferred income tax assets	0	0
Georgia Power | Long-term debt fair value adjustment
Deferred tax assets —
Deferred income tax assets	0	0
Georgia Power | Other comprehensive losses
Deferred tax assets —
Deferred income tax assets	4	5
Georgia Power | Other
Deferred tax assets —
Deferred income tax assets	152	186
Georgia Power | AROs
Deferred tax assets —
Deferred income tax assets	1,510	1,609
Mississippi Power
Deferred tax liabilities —
Deferred income tax liabilities	714	717
Deferred tax assets —
Deferred income tax assets	382	399
Valuation allowance	(41)	(41)
Net deferred income tax assets	341	358
Net deferred income taxes liabilities	373	359
Accumulated deferred income taxes – assets	(96)	(107)
Accumulated deferred income taxes – liabilities	469	466
Mississippi Power | Accelerated depreciation
Deferred tax liabilities —
Deferred income tax liabilities	339	338
Mississippi Power | Property basis differences
Deferred tax liabilities —
Deferred income tax liabilities	188	179
Mississippi Power | Employee benefit obligations
Deferred tax liabilities —
Deferred income tax liabilities	49	43
Deferred tax assets —
Deferred income tax assets	52	47
Mississippi Power | AROs
Deferred tax liabilities —
Deferred income tax liabilities	0	0
Mississippi Power | Under recovered fuel and natural gas costs
Deferred tax liabilities —
Deferred income tax liabilities	13	40
Mississippi Power | AROs
Deferred tax liabilities —
Deferred income tax liabilities	39	42
Mississippi Power | Employee benefit obligations
Deferred tax liabilities —
Deferred income tax liabilities	37	30
Mississippi Power | Remaining book value of retired assets
Deferred tax liabilities —
Deferred income tax liabilities	5	5
Mississippi Power | Premium on reacquired debt
Deferred tax liabilities —
Deferred income tax liabilities	1	0
Mississippi Power | Other
Deferred tax liabilities —
Deferred income tax liabilities	43	40
Mississippi Power | ITC and PTC carryforwards
Deferred tax assets —
Deferred income tax assets	0	0
Mississippi Power | Estimated loss on plants under construction
Deferred tax assets —
Deferred income tax assets	0	0
Mississippi Power | Estimated loss on regulatory disallowance
Deferred tax assets —
Deferred income tax assets	0
Mississippi Power | Other state deferred tax attributes
Deferred tax assets —
Deferred income tax assets	231	239
Mississippi Power | Federal effect of net state deferred tax assets/liabilities
Deferred tax assets —
Deferred income tax assets	0	0
Mississippi Power | Other property basis differences
Deferred tax assets —
Deferred income tax assets	0	0
Mississippi Power | State effect of federal deferred taxes
Deferred tax assets —
Deferred income tax assets	0	0
Mississippi Power | Other partnership basis differences
Deferred tax assets —
Deferred income tax assets	0	0
Mississippi Power | Regulatory liability associated with the Tax Reform Legislation (not subject to normalization)
Deferred tax assets —
Deferred income tax assets	3	9
Mississippi Power | Long-term debt fair value adjustment
Deferred tax assets —
Deferred income tax assets	0	0
Mississippi Power | Other comprehensive losses
Deferred tax assets —
Deferred income tax assets	0	0
Mississippi Power | Other
Deferred tax assets —
Deferred income tax assets	57	62
Mississippi Power | AROs
Deferred tax assets —
Deferred income tax assets	39	42
Southern Power
Deferred tax liabilities —
Deferred income tax liabilities	1,360	1,376
Deferred tax assets —
Deferred income tax assets	773	1,124
Valuation allowance	(27)	(27)
Net deferred income tax assets	746	1,097
Net deferred income taxes liabilities	614	279
Accumulated deferred income taxes – assets	0	0
Accumulated deferred income taxes – liabilities	614	279
Southern Power | Accelerated depreciation
Deferred tax liabilities —
Deferred income tax liabilities	1,346	1,351
Southern Power | Property basis differences
Deferred tax liabilities —
Deferred income tax liabilities	0	0
Southern Power | Employee benefit obligations
Deferred tax liabilities —
Deferred income tax liabilities	12	11
Deferred tax assets —
Deferred income tax assets	10	9
Southern Power | AROs
Deferred tax liabilities —
Deferred income tax liabilities	0	0
Southern Power | Under recovered fuel and natural gas costs
Deferred tax liabilities —
Deferred income tax liabilities	0	0
Southern Power | AROs
Deferred tax liabilities —
Deferred income tax liabilities	0	0
Southern Power | Employee benefit obligations
Deferred tax liabilities —
Deferred income tax liabilities	0	0
Southern Power | Remaining book value of retired assets
Deferred tax liabilities —
Deferred income tax liabilities	0	0
Southern Power | Premium on reacquired debt
Deferred tax liabilities —
Deferred income tax liabilities	0	0
Southern Power | Other
Deferred tax liabilities —
Deferred income tax liabilities	2	14
Southern Power | ITC and PTC carryforwards
Deferred tax assets —
Deferred income tax assets	481	794
Southern Power | Estimated loss on plants under construction
Deferred tax assets —
Deferred income tax assets	0	0
Southern Power | Estimated loss on regulatory disallowance
Deferred tax assets —
Deferred income tax assets	0
Southern Power | Other state deferred tax attributes
Deferred tax assets —
Deferred income tax assets	49	51
Southern Power | Federal effect of net state deferred tax assets/liabilities
Deferred tax assets —
Deferred income tax assets	27	28
Southern Power | Other property basis differences
Deferred tax assets —
Deferred income tax assets	97	109
Southern Power | State effect of federal deferred taxes
Deferred tax assets —
Deferred income tax assets	0	0
Southern Power | Other partnership basis differences
Deferred tax assets —
Deferred income tax assets	85	111
Southern Power | Regulatory liability associated with the Tax Reform Legislation (not subject to normalization)
Deferred tax assets —
Deferred income tax assets	0	0
Southern Power | Long-term debt fair value adjustment
Deferred tax assets —
Deferred income tax assets	0	0
Southern Power | Other comprehensive losses
Deferred tax assets —
Deferred income tax assets	6	5
Southern Power | Other
Deferred tax assets —
Deferred income tax assets	18	17
Southern Power | AROs
Deferred tax assets —
Deferred income tax assets	0	0
Southern Company Gas
Deferred tax liabilities —
Deferred income tax liabilities	2,041	1,852
Deferred tax assets —
Deferred income tax assets	377	301
Valuation allowance	(7)	(9)
Net deferred income tax assets	370	292
Net deferred income taxes liabilities	1,671	1,560
Accumulated deferred income taxes – assets	0	0
Accumulated deferred income taxes – liabilities	1,671	1,560
Southern Company Gas | Accelerated depreciation
Deferred tax liabilities —
Deferred income tax liabilities	1,576	1,505
Southern Company Gas | Property basis differences
Deferred tax liabilities —
Deferred income tax liabilities	189	150
Southern Company Gas | Employee benefit obligations
Deferred tax liabilities —
Deferred income tax liabilities	74	68
Deferred tax assets —
Deferred income tax assets	89	89
Southern Company Gas | AROs
Deferred tax liabilities —
Deferred income tax liabilities	0	0
Southern Company Gas | Under recovered fuel and natural gas costs
Deferred tax liabilities —
Deferred income tax liabilities	0	32
Southern Company Gas | AROs
Deferred tax liabilities —
Deferred income tax liabilities	0	0
Southern Company Gas | Employee benefit obligations
Deferred tax liabilities —
Deferred income tax liabilities	11	15
Southern Company Gas | Remaining book value of retired assets
Deferred tax liabilities —
Deferred income tax liabilities	0	0
Southern Company Gas | Premium on reacquired debt
Deferred tax liabilities —
Deferred income tax liabilities	0	0
Southern Company Gas | Other
Deferred tax liabilities —
Deferred income tax liabilities	191	82
Southern Company Gas | ITC and PTC carryforwards
Deferred tax assets —
Deferred income tax assets	0	0
Southern Company Gas | Estimated loss on plants under construction
Deferred tax assets —
Deferred income tax assets	0	0
Southern Company Gas | Estimated loss on regulatory disallowance
Deferred tax assets —
Deferred income tax assets	26
Southern Company Gas | Other state deferred tax attributes
Deferred tax assets —
Deferred income tax assets	8	7
Southern Company Gas | Federal effect of net state deferred tax assets/liabilities
Deferred tax assets —
Deferred income tax assets	101	92
Southern Company Gas | Other property basis differences
Deferred tax assets —
Deferred income tax assets	0	0
Southern Company Gas | State effect of federal deferred taxes
Deferred tax assets —
Deferred income tax assets	0	0
Southern Company Gas | Other partnership basis differences
Deferred tax assets —
Deferred income tax assets	0	0
Southern Company Gas | Regulatory liability associated with the Tax Reform Legislation (not subject to normalization)
Deferred tax assets —
Deferred income tax assets	0	0
Southern Company Gas | Long-term debt fair value adjustment
Deferred tax assets —
Deferred income tax assets	79	85
Southern Company Gas | Other comprehensive losses
Deferred tax assets —
Deferred income tax assets	0	0
Southern Company Gas | Other
Deferred tax assets —
Deferred income tax assets	74	28
Southern Company Gas | AROs
Deferred tax assets —
Deferred income tax assets	$ 0	$ 0