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, 2022	Jun. 30, 2021	Jun. 30, 2022	Jun. 30, 2021
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	$ 6,226	$ 5,422	$ 12,486	$ 12,319
Total operating revenues	7,206	5,198	13,854	11,108
Retail electric revenues
Disaggregation of Revenue [Line Items]
Total operating revenues	4,789	3,599	8,402	6,941
Retail electric revenues
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	4,072	3,396	7,529	6,674
Residential
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	1,655	1,469	3,179	2,936
Commercial
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	1,387	1,176	2,567	2,294
Industrial
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	1,005	728	1,732	1,397
Other
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	25	23	51	47
Natural Gas
Disaggregation of Revenue [Line Items]
Total operating revenues	1,083	677	3,140	2,371
Natural gas distribution revenues
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	963	698	2,746	1,883
Residential
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	474	311	1,490	925
Commercial
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	130	73	400	243
Transportation
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	276	247	613	536
Industrial
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	16	8	48	24
Other
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	67	59	195	155
Other natural gas revenues
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	100	651	359	2,442
Wholesale gas services
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers		578		2,168
Gas marketing services
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	90	63	333	257
Other natural gas revenues
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	10	10	26	17
Other revenue sources
Disaggregation of Revenue [Line Items]
Other revenues	980	1,179	1,368	2,488
Other adjustments
Disaggregation of Revenue [Line Items]
Other revenues		(1,403)		(3,699)
Wholesale Electric
Disaggregation of Revenue [Line Items]
Total operating revenues	937	546	1,601	1,091
Wholesale electric revenues
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	783	382	1,322	778
PPA energy revenues
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	585	209	930	422
PPA capacity revenues
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	136	118	268	237
Non-PPA revenues
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	62	55	124	119
Other revenues
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	308	295	530	542
ALABAMA POWER CO
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	1,644	1,421	3,188	2,895
Total operating revenues	1,931	1,556	3,580	3,115
ALABAMA POWER CO | Retail electric revenues
Disaggregation of Revenue [Line Items]
Total operating revenues	1,629	1,354	3,008	2,706
ALABAMA POWER CO | Retail electric revenues
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	1,398	1,277	2,734	2,602
ALABAMA POWER CO | Residential
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	617	553	1,250	1,181
ALABAMA POWER CO | Commercial
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	410	386	786	758
ALABAMA POWER CO | Industrial
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	368	334	691	654
ALABAMA POWER CO | Other
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	3	4	7	9
ALABAMA POWER CO | Natural gas distribution revenues
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	0	0	0	0
ALABAMA POWER CO | Residential
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	0	0	0	0
ALABAMA POWER CO | Commercial
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	0	0	0	0
ALABAMA POWER CO | Transportation
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	0	0	0	0
ALABAMA POWER CO | Industrial
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	0	0	0	0
ALABAMA POWER CO | Other
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	0	0	0	0
ALABAMA POWER CO | Other natural gas revenues
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	0	0	0	0
ALABAMA POWER CO | Wholesale gas services
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers		0		0
ALABAMA POWER CO | Gas marketing services
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	0	0	0	0
ALABAMA POWER CO | Other natural gas revenues
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	0	0	0	0
ALABAMA POWER CO | Other revenue sources
Disaggregation of Revenue [Line Items]
Other revenues	287	135	392	220
ALABAMA POWER CO | Other adjustments
Disaggregation of Revenue [Line Items]
Other revenues		0		0
ALABAMA POWER CO | Wholesale electric revenues
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	183	92	345	196
ALABAMA POWER CO | PPA energy revenues
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	108	38	168	81
ALABAMA POWER CO | PPA capacity revenues
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	40	29	78	58
ALABAMA POWER CO | Non-PPA revenues
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	35	25	99	57
ALABAMA POWER CO | Other revenues
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	63	52	109	97
GEORGIA POWER CO
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	2,614	2,084	4,674	3,995
Total operating revenues	3,121	2,225	5,328	4,195
GEORGIA POWER CO | Retail electric revenues
Disaggregation of Revenue [Line Items]
Total operating revenues	2,908	2,026	4,926	3,813
GEORGIA POWER CO | Retail electric revenues
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	2,435	1,914	4,348	3,677
GEORGIA POWER CO | Residential
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	962	852	1,783	1,627
GEORGIA POWER CO | Commercial
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	900	724	1,638	1,410
GEORGIA POWER CO | Industrial
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	553	321	887	606
GEORGIA POWER CO | Other
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	20	17	40	34
GEORGIA POWER CO | Natural gas distribution revenues
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	0	0	0	0
GEORGIA POWER CO | Residential
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	0	0	0	0
GEORGIA POWER CO | Commercial
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	0	0	0	0
GEORGIA POWER CO | Transportation
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	0	0	0	0
GEORGIA POWER CO | Industrial
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	0	0	0	0
GEORGIA POWER CO | Other
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	0	0	0	0
GEORGIA POWER CO | Other natural gas revenues
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	0	0	0	0
GEORGIA POWER CO | Wholesale gas services
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers		0		0
GEORGIA POWER CO | Gas marketing services
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	0	0	0	0
GEORGIA POWER CO | Other natural gas revenues
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	0	0	0	0
GEORGIA POWER CO | Other revenue sources
Disaggregation of Revenue [Line Items]
Other revenues	507	141	654	200
GEORGIA POWER CO | Other adjustments
Disaggregation of Revenue [Line Items]
Other revenues		0		0
GEORGIA POWER CO | Wholesale Electric
Disaggregation of Revenue [Line Items]
Total operating revenues	64	36	130	80
GEORGIA POWER CO | Wholesale electric revenues
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	58	33	110	69
GEORGIA POWER CO | PPA energy revenues
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	40	16	72	30
GEORGIA POWER CO | PPA capacity revenues
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	12	14	23	27
GEORGIA POWER CO | Non-PPA revenues
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	6	3	15	12
GEORGIA POWER CO | Other revenues
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	121	137	216	249
MISSISSIPPI POWER CO
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	422	290	746	582
Total operating revenues	434	303	769	610
MISSISSIPPI POWER CO | Retail electric revenues
Disaggregation of Revenue [Line Items]
Total operating revenues	252	219	469	422
MISSISSIPPI POWER CO | Retail electric revenues
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	239	205	447	395
MISSISSIPPI POWER CO | Residential
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	76	64	146	128
MISSISSIPPI POWER CO | Commercial
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	77	66	143	126
MISSISSIPPI POWER CO | Industrial
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	84	73	154	137
MISSISSIPPI POWER CO | Other
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	2	2	4	4
MISSISSIPPI POWER CO | Natural gas distribution revenues
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	0	0	0	0
MISSISSIPPI POWER CO | Residential
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	0	0	0	0
MISSISSIPPI POWER CO | Commercial
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	0	0	0	0
MISSISSIPPI POWER CO | Transportation
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	0	0	0	0
MISSISSIPPI POWER CO | Industrial
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	0	0	0	0
MISSISSIPPI POWER CO | Other
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	0	0	0	0
MISSISSIPPI POWER CO | Other natural gas revenues
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	0	0	0	0
MISSISSIPPI POWER CO | Wholesale gas services
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers		0		0
MISSISSIPPI POWER CO | Gas marketing services
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	0	0	0	0
MISSISSIPPI POWER CO | Other natural gas revenues
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	0	0	0	0
MISSISSIPPI POWER CO | Other revenue sources
Disaggregation of Revenue [Line Items]
Other revenues	12	13	23	28
MISSISSIPPI POWER CO | Other adjustments
Disaggregation of Revenue [Line Items]
Other revenues		0		0
MISSISSIPPI POWER CO | Wholesale electric revenues
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	174	78	282	173
MISSISSIPPI POWER CO | PPA energy revenues
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	5	2	8	7
MISSISSIPPI POWER CO | PPA capacity revenues
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	0	1	3	4
MISSISSIPPI POWER CO | Non-PPA revenues
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	169	75	271	162
MISSISSIPPI POWER CO | Other revenues
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	9	7	17	14
SOUTHERN POWER CO
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	731	316	1,146	611
Total operating revenues	899	490	1,438	930
SOUTHERN POWER CO | Retail electric revenues
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	0	0	0	0
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 | Natural gas distribution revenues
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	0	0	0	0
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 | Transportation
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 | Other natural gas revenues
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	0	0	0	0
SOUTHERN POWER CO | Wholesale gas services
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers		0		0
SOUTHERN POWER CO | Gas marketing services
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	0	0	0	0
SOUTHERN POWER CO | Other natural gas revenues
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	0	0	0	0
SOUTHERN POWER CO | Other revenue sources
Disaggregation of Revenue [Line Items]
Other revenues	168	174	292	319
SOUTHERN POWER CO | Other adjustments
Disaggregation of Revenue [Line Items]
Other revenues		0		0
SOUTHERN POWER CO | Wholesale electric revenues
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	722	311	1,129	602
SOUTHERN POWER CO | PPA energy revenues
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	441	158	694	313
SOUTHERN POWER CO | PPA capacity revenues
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	85	75	166	150
SOUTHERN POWER CO | Non-PPA revenues
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	196	78	269	139
SOUTHERN POWER CO | Other revenues
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	9	5	17	9
SOUTHERN Co GAS
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	1,063	1,349	3,105	4,325
Total operating revenues	1,083	677	3,140	2,371
SOUTHERN Co GAS | Retail electric revenues
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	0	0	0	0
SOUTHERN Co GAS | Residential
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	0	0	0	0
SOUTHERN Co GAS | Commercial
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	0	0	0	0
SOUTHERN Co GAS | Industrial
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	0	0	0	0
SOUTHERN Co GAS | Other
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	0	0	0	0
SOUTHERN Co GAS | Natural gas distribution revenues
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	963	698	2,746	1,883
SOUTHERN Co GAS | Residential
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	474	311	1,490	925
SOUTHERN Co GAS | Commercial
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	130	73	400	243
SOUTHERN Co GAS | Transportation
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	276	247	613	536
SOUTHERN Co GAS | Industrial
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	16	8	48	24
SOUTHERN Co GAS | Other
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	67	59	195	155
SOUTHERN Co GAS | Other natural gas revenues
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	100	651	359	2,442
SOUTHERN Co GAS | Wholesale gas services
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers		578		2,168
SOUTHERN Co GAS | Gas marketing services
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	90	63	333	257
SOUTHERN Co GAS | Other natural gas revenues
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	10	10	26	17
SOUTHERN Co GAS | Other revenue sources
Disaggregation of Revenue [Line Items]
Other revenues	20	731	35	1,745
SOUTHERN Co GAS | Other adjustments
Disaggregation of Revenue [Line Items]
Other revenues		(1,403)		(3,699)
SOUTHERN Co GAS | Wholesale electric revenues
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	0	0	0	0
SOUTHERN Co GAS | PPA energy revenues
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	0	0	0	0
SOUTHERN Co GAS | PPA capacity revenues
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	0	0	0	0
SOUTHERN Co GAS | Non-PPA revenues
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	0	0	0	0
SOUTHERN Co GAS | Other revenues
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	$ 0	$ 0	$ 0	$ 0