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, 2025	Jun. 30, 2024	Jun. 30, 2025	Jun. 30, 2024
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	$ 6,734	$ 6,347	$ 14,328	$ 13,028
Total operating revenues	6,973	6,463	14,748	13,109
Residential
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	2,021	2,049	4,087	3,900
Commercial
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	1,716	1,613	3,327	3,084
Industrial
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	1,015	962	1,930	1,834
Other
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	29	30	61	60
Retail electric revenues
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	4,781	4,654	9,405	8,878
Natural gas distribution revenues
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	886	728	2,464	2,140
Residential
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	394	287	1,239	1,032
Commercial
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	94	69	292	245
Transportation
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	331	304	737	666
Industrial
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	7	5	26	21
Other
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	60	63	170	176
Wholesale electric revenues
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	524	472	1,158	953
PPA energy revenues
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	310	265	723	537
PPA capacity revenues
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	154	153	299	304
Non-PPA revenues
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	60	54	136	112
Other natural gas revenues
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	86	74	347	311
Gas marketing services
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	81	68	337	300
Other
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	5	6	10	11
Other revenues
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	457	419	954	746
Other revenue sources
Disaggregation of Revenue [Line Items]
Other revenues	239	116	420	81
ALABAMA POWER CO
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	1,853	1,859	3,768	3,678
Total operating revenues	1,968	1,873	3,980	3,664
ALABAMA POWER CO | Residential
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	725	736	1,531	1,501
ALABAMA POWER CO | Commercial
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	504	508	986	976
ALABAMA POWER CO | Industrial
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	432	445	822	855
ALABAMA POWER CO | Other
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	2	3	4	6
ALABAMA POWER CO | Retail electric revenues
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	1,663	1,692	3,343	3,338
ALABAMA POWER CO | Wholesale electric revenues
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	123	105	275	226
ALABAMA POWER CO | PPA energy revenues
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	58	55	112	112
ALABAMA POWER CO | PPA capacity revenues
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	29	23	57	46
ALABAMA POWER CO | Non-PPA revenues
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	36	27	106	68
ALABAMA POWER CO | Other revenues
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	67	62	150	114
ALABAMA POWER CO | Other revenue sources
Disaggregation of Revenue [Line Items]
Other revenues	115	14	212	(14)
GEORGIA POWER CO
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	3,166	2,959	6,239	5,517
Total operating revenues	3,110	2,875	6,148	5,273
GEORGIA POWER CO | Residential
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	1,217	1,236	2,403	2,252
GEORGIA POWER CO | Commercial
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	1,127	1,023	2,181	1,955
GEORGIA POWER CO | Industrial
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	496	434	940	817
GEORGIA POWER CO | Other
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	25	25	52	50
GEORGIA POWER CO | Retail electric revenues
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	2,865	2,718	5,576	5,074
GEORGIA POWER CO | Wholesale electric revenues
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	95	56	227	106
GEORGIA POWER CO | PPA energy revenues
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	50	22	134	40
GEORGIA POWER CO | PPA capacity revenues
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	35	32	74	64
GEORGIA POWER CO | Non-PPA revenues
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	10	2	19	2
GEORGIA POWER CO | Other revenues
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	206	185	436	337
GEORGIA POWER CO | Other revenue sources
Disaggregation of Revenue [Line Items]
Other revenues	(56)	(84)	(91)	(244)
MISSISSIPPI POWER CO
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	381	365	788	708
Total operating revenues	400	364	821	706
MISSISSIPPI POWER CO | Residential
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	79	77	153	147
MISSISSIPPI POWER CO | Commercial
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	85	82	160	153
MISSISSIPPI POWER CO | Industrial
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	87	83	168	162
MISSISSIPPI POWER CO | Other
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	2	2	5	4
MISSISSIPPI POWER CO | Retail electric revenues
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	253	244	486	466
MISSISSIPPI POWER CO | Wholesale electric revenues
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	119	111	272	220
MISSISSIPPI POWER CO | PPA energy revenues
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	2	1	5	2
MISSISSIPPI POWER CO | PPA capacity revenues
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	17	15	34	31
MISSISSIPPI POWER CO | Non-PPA revenues
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	100	95	233	187
MISSISSIPPI POWER CO | Other revenues
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	9	10	30	22
MISSISSIPPI POWER CO | Other revenue sources
Disaggregation of Revenue [Line Items]
Other revenues	19	(1)	33	(2)
SOUTHERN POWER CO
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	362	352	795	721
Total operating revenues	546	524	1,113	997
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	354	341	781	700
SOUTHERN POWER CO | PPA energy revenues
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	210	192	491	394
SOUTHERN POWER CO | PPA capacity revenues
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	85	99	169	196
SOUTHERN POWER CO | Non-PPA revenues
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	59	50	121	110
SOUTHERN POWER CO | Other revenues
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	8	11	14	21
SOUTHERN POWER CO | Other revenue sources
Disaggregation of Revenue [Line Items]
Other revenues	184	172	318	276
SOUTHERN Co GAS
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	972	802	2,811	2,451
Total operating revenues	979	831	2,818	2,538
SOUTHERN Co GAS | Natural gas distribution revenues
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	886	728	2,464	2,140
SOUTHERN Co GAS | Residential
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	394	287	1,239	1,032
SOUTHERN Co GAS | Commercial
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	94	69	292	245
SOUTHERN Co GAS | Transportation
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	331	304	737	666
SOUTHERN Co GAS | Industrial
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	7	5	26	21
SOUTHERN Co GAS | Other
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	60	63	170	176
SOUTHERN Co GAS | Other natural gas revenues
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	86	74	347	311
SOUTHERN Co GAS | Gas marketing services
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	81	68	337	300
SOUTHERN Co GAS | Other
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	5	6	10	11
SOUTHERN Co GAS | Other revenues
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	0	0	0	0
SOUTHERN Co GAS | Other revenue sources
Disaggregation of Revenue [Line Items]
Other revenues	$ 7	$ 29	$ 7	$ 87