Revenue from Contracts with Customers and Lease Income - Schedule of Disaggregation of Revenue (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2024	Jun. 30, 2023	Jun. 30, 2024	Jun. 30, 2023
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	$ 6,347	$ 5,532	$ 13,028	$ 11,777
Total operating revenues	6,463	5,748	13,109	12,228
Residential
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	2,049	1,647	3,900	3,174
Commercial
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	1,613	1,370	3,084	2,619
Industrial
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	962	864	1,834	1,653
Other
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	30	27	60	54
Retail electric revenues
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	4,654	3,908	8,878	7,500
Natural gas distribution revenues
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	728	753	2,140	2,340
Residential
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	287	330	1,032	1,226
Commercial
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	69	82	245	314
Transportation
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	304	284	666	603
Industrial
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	5	6	21	29
Other
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	63	51	176	168
Wholesale electric revenues
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	472	463	953	973
PPA energy revenues
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	265	253	537	534
PPA capacity revenues
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	153	149	304	341
Non-PPA revenues
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	54	61	112	98
Other natural gas revenues
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	74	81	311	324
Gas marketing services
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	68	73	300	304
Other
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	6	8	11	20
Other revenue sources
Disaggregation of Revenue [Line Items]
Other revenues	116	216	81	451
Other revenues
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	419	327	746	640
ALABAMA POWER CO
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	1,859	1,702	3,678	3,404
Total operating revenues	1,873	1,689	3,664	3,336
ALABAMA POWER CO | Residential
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	736	648	1,501	1,308
ALABAMA POWER CO | Commercial
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	508	465	976	894
ALABAMA POWER CO | Industrial
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	445	429	855	827
ALABAMA POWER CO | Other
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	3	3	6	6
ALABAMA POWER CO | Retail electric revenues
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	1,692	1,545	3,338	3,035
ALABAMA POWER CO | Wholesale electric revenues
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	105	114	226	266
ALABAMA POWER CO | PPA energy revenues
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	55	58	112	129
ALABAMA POWER CO | PPA capacity revenues
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	23	44	46	105
ALABAMA POWER CO | Non-PPA revenues
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	27	12	68	32
ALABAMA POWER CO | Other revenue sources
Disaggregation of Revenue [Line Items]
Other revenues	14	(13)	(14)	(68)
ALABAMA POWER CO | Other revenues
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	62	43	114	103
GEORGIA POWER CO
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	2,959	2,321	5,517	4,368
Total operating revenues	2,875	2,391	5,273	4,567
GEORGIA POWER CO | Residential
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	1,236	928	2,252	1,730
GEORGIA POWER CO | Commercial
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	1,023	830	1,955	1,582
GEORGIA POWER CO | Industrial
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	434	353	817	666
GEORGIA POWER CO | Other
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	25	22	50	44
GEORGIA POWER CO | Retail electric revenues
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	2,718	2,133	5,074	4,022
GEORGIA POWER CO | Wholesale electric revenues
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	56	43	106	70
GEORGIA POWER CO | PPA energy revenues
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	22	24	40	35
GEORGIA POWER CO | PPA capacity revenues
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	32	13	64	25
GEORGIA POWER CO | Non-PPA revenues
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	2	6	2	10
GEORGIA POWER CO | Other revenue sources
Disaggregation of Revenue [Line Items]
Other revenues	(84)	70	(244)	199
GEORGIA POWER CO | Other revenues
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	185	145	337	276
MISSISSIPPI POWER CO
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	365	314	708	682
Total operating revenues	364	311	706	702
MISSISSIPPI POWER CO | Residential
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	77	71	147	136
MISSISSIPPI POWER CO | Commercial
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	82	75	153	143
MISSISSIPPI POWER CO | Industrial
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	83	82	162	160
MISSISSIPPI POWER CO | Other
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	2	2	4	4
MISSISSIPPI POWER CO | Retail electric revenues
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	244	230	466	443
MISSISSIPPI POWER CO | Wholesale electric revenues
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	111	74	220	217
MISSISSIPPI POWER CO | PPA energy revenues
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	1	2	2	5
MISSISSIPPI POWER CO | PPA capacity revenues
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	15	2	31	34
MISSISSIPPI POWER CO | Non-PPA revenues
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	95	70	187	178
MISSISSIPPI POWER CO | Other revenue sources
Disaggregation of Revenue [Line Items]
Other revenues	(1)	(3)	(2)	20
MISSISSIPPI POWER CO | Other revenues
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	10	10	22	22
SOUTHERN POWER CO
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	352	365	721	769
Total operating revenues	524	525	997	1,033
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	341	349	700	742
SOUTHERN POWER CO | PPA energy revenues
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	192	175	394	376
SOUTHERN POWER CO | PPA capacity revenues
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	99	91	196	179
SOUTHERN POWER CO | Non-PPA revenues
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	50	83	110	187
SOUTHERN POWER CO | Other revenue sources
Disaggregation of Revenue [Line Items]
Other revenues	172	160	276	264
SOUTHERN POWER CO | Other revenues
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	11	16	21	27
SOUTHERN Co GAS
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	802	834	2,451	2,664
Total operating revenues	831	852	2,538	2,728
SOUTHERN Co GAS | Natural gas distribution revenues
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	728	753	2,140	2,340
SOUTHERN Co GAS | Residential
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	287	330	1,032	1,226
SOUTHERN Co GAS | Commercial
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	69	82	245	314
SOUTHERN Co GAS | Transportation
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	304	284	666	603
SOUTHERN Co GAS | Industrial
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	5	6	21	29
SOUTHERN Co GAS | Other
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	63	51	176	168
SOUTHERN Co GAS | Other natural gas revenues
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	74	81	311	324
SOUTHERN Co GAS | Gas marketing services
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	68	73	300	304
SOUTHERN Co GAS | Other
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	6	8	11	20
SOUTHERN Co GAS | Other revenue sources
Disaggregation of Revenue [Line Items]
Other revenues	29	18	87	64
SOUTHERN Co GAS | Other revenues
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	$ 0	$ 0	$ 0	$ 0