Revenue from Contracts with Customers and Lease Income - Schedule of Disaggregation of Revenue (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2024	Sep. 30, 2023	Sep. 30, 2024	Sep. 30, 2023
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	$ 7,481	$ 7,107	$ 20,513	$ 18,886
Total operating revenues	7,274	6,980	20,383	19,208
Residential
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	2,651	2,543	6,551	5,717
Commercial
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	1,991	1,845	5,075	4,464
Industrial
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	1,184	1,116	3,019	2,770
Other
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	33	30	94	84
Retail electric revenues
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	5,859	5,534	14,739	13,035
Natural gas distribution revenues
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	610	612	2,749	2,952
Residential
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	212	217	1,244	1,443
Commercial
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	55	56	300	370
Transportation
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	294	275	959	878
Industrial
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	4	4	25	33
Other
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	45	60	221	228
Wholesale electric revenues
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	557	569	1,512	1,542
PPA energy revenues
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	300	317	838	853
PPA capacity revenues
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	190	151	495	490
Non-PPA revenues
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	67	101	179	199
Other natural gas revenues
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	57	62	368	386
Gas marketing services
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	51	54	352	358
Other
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	6	8	16	28
Other revenue sources
Disaggregation of Revenue [Line Items]
Other revenues	(207)	(127)	(130)	322
Other revenues
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	398	330	1,145	971
ALABAMA POWER CO
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	2,244	2,230	5,926	5,638
Total operating revenues	2,138	2,083	5,803	5,420
ALABAMA POWER CO | Residential
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	975	969	2,477	2,277
ALABAMA POWER CO | Commercial
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	607	599	1,583	1,493
ALABAMA POWER CO | Industrial
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	483	498	1,338	1,324
ALABAMA POWER CO | Other
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	3	3	9	10
ALABAMA POWER CO | Retail electric revenues
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	2,068	2,069	5,407	5,104
ALABAMA POWER CO | Wholesale electric revenues
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	116	107	345	375
ALABAMA POWER CO | PPA energy revenues
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	58	66	171	196
ALABAMA POWER CO | PPA capacity revenues
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	24	26	71	130
ALABAMA POWER CO | Non-PPA revenues
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	34	15	103	49
ALABAMA POWER CO | Other revenue sources
Disaggregation of Revenue [Line Items]
Other revenues	(106)	(147)	(123)	(218)
ALABAMA POWER CO | Other revenues
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	60	54	174	159
GEORGIA POWER CO
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	3,740	3,388	9,259	7,754
Total operating revenues	3,472	3,237	8,745	7,805
GEORGIA POWER CO | Residential
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	1,580	1,473	3,832	3,202
GEORGIA POWER CO | Commercial
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	1,288	1,151	3,243	2,733
GEORGIA POWER CO | Industrial
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	606	528	1,424	1,195
GEORGIA POWER CO | Other
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	28	25	78	68
GEORGIA POWER CO | Retail electric revenues
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	3,502	3,177	8,577	7,198
GEORGIA POWER CO | Wholesale electric revenues
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	68	65	175	134
GEORGIA POWER CO | PPA energy revenues
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	26	31	66	66
GEORGIA POWER CO | PPA capacity revenues
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	42	13	106	38
GEORGIA POWER CO | Non-PPA revenues
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	0	21	3	30
GEORGIA POWER CO | Other revenue sources
Disaggregation of Revenue [Line Items]
Other revenues	(268)	(151)	(514)	51
GEORGIA POWER CO | Other revenues
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	170	146	507	422
MISSISSIPPI POWER CO
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	424	440	1,131	1,123
Total operating revenues	412	436	1,118	1,137
MISSISSIPPI POWER CO | Residential
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	96	101	242	238
MISSISSIPPI POWER CO | Commercial
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	96	95	249	238
MISSISSIPPI POWER CO | Industrial
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	95	90	257	251
MISSISSIPPI POWER CO | Other
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	2	2	7	6
MISSISSIPPI POWER CO | Retail electric revenues
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	289	288	755	733
MISSISSIPPI POWER CO | Wholesale electric revenues
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	122	142	342	359
MISSISSIPPI POWER CO | PPA energy revenues
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	1	2	3	8
MISSISSIPPI POWER CO | PPA capacity revenues
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	15	3	47	36
MISSISSIPPI POWER CO | Non-PPA revenues
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	106	137	292	315
MISSISSIPPI POWER CO | Other revenue sources
Disaggregation of Revenue [Line Items]
Other revenues	(12)	(4)	(13)	14
MISSISSIPPI POWER CO | Other revenues
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	13	10	34	31
SOUTHERN POWER CO
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	423	480	1,143	1,248
Total operating revenues	600	653	1,597	1,686
SOUTHERN POWER CO | Residential
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	0	0	0	0
SOUTHERN POWER CO | Commercial
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	0	0	0	0
SOUTHERN POWER CO | Industrial
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	0	0	0	0
SOUTHERN POWER CO | Other
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	0	0	0	0
SOUTHERN POWER CO | Retail electric revenues
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	0	0	0	0
SOUTHERN POWER CO | Wholesale electric revenues
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	414	462	1,112	1,202
SOUTHERN POWER CO | PPA energy revenues
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	222	226	616	601
SOUTHERN POWER CO | PPA capacity revenues
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	125	110	320	289
SOUTHERN POWER CO | Non-PPA revenues
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	67	126	176	312
SOUTHERN POWER CO | Other revenue sources
Disaggregation of Revenue [Line Items]
Other revenues	177	173	454	438
SOUTHERN POWER CO | Other revenues
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	9	18	31	46
SOUTHERN Co GAS
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	667	674	3,117	3,338
Total operating revenues	682	689	3,220	3,417
SOUTHERN Co GAS | Natural gas distribution revenues
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	610	612	2,749	2,952
SOUTHERN Co GAS | Residential
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	212	217	1,244	1,443
SOUTHERN Co GAS | Commercial
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	55	56	300	370
SOUTHERN Co GAS | Transportation
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	294	275	959	878
SOUTHERN Co GAS | Industrial
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	4	4	25	33
SOUTHERN Co GAS | Other
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	45	60	221	228
SOUTHERN Co GAS | Other natural gas revenues
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	57	62	368	386
SOUTHERN Co GAS | Gas marketing services
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	51	54	352	358
SOUTHERN Co GAS | Other
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	6	8	16	28
SOUTHERN Co GAS | Other revenue sources
Disaggregation of Revenue [Line Items]
Other revenues	15	15	103	79
SOUTHERN Co GAS | Other revenues
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	$ 0	$ 0	$ 0	$ 0