Segment and Related Information - Schedule of Financial Data for Business Segments (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2022	Jun. 30, 2021	Jun. 30, 2022	Jun. 30, 2021	Dec. 31, 2021
Segment Reporting Information [Line Items]
Operating revenues	$ 7,206	$ 5,198	$ 13,854	$ 11,108
Segment net income (loss)	1,107	372	2,139	1,508
Goodwill	5,280		5,280		$ 5,280
Total assets	130,769		130,769		127,534
Estimated loss on Plant Vogtle Units 3 and 4	52	460	52	508
GEORGIA POWER CO
Segment Reporting Information [Line Items]
Operating revenues	3,121	2,225	5,328	4,195
Total assets	50,974		50,974		48,461
Estimated loss on Plant Vogtle Units 3 and 4	52	460	52	508
Estimated loss on Plant Vogtle Units 3 and 4, net of tax	39	343	39	379
SOUTHERN POWER CO
Segment Reporting Information [Line Items]
Operating revenues	899	490	1,438	930
Segment net income (loss)	98	36	170	133
Total assets	13,402		13,402		13,390
Gain on sale			2	39
SOUTHERN POWER CO | Wind Generating Facility
Segment Reporting Information [Line Items]
Gain on sale				37
Gain on sale, net of tax				28
SOUTHERN Co GAS
Segment Reporting Information [Line Items]
Operating revenues	1,083	677	3,140	2,371
Segment net income (loss)	115	(65)	433	333
Goodwill	5,015		5,015		5,015
Total assets	23,618		23,618		23,560
Impairment of PennEast Pipeline investment			0	82
SOUTHERN Co GAS | PennEast Pipeline
Segment Reporting Information [Line Items]
Impairment of PennEast Pipeline investment		82		82
Asset impairment charges, net of tax		58		58
Electric Utilities
Segment Reporting Information [Line Items]
Operating revenues	6,006	4,407	10,516	8,524
SOUTHERN Co GAS
Segment Reporting Information [Line Items]
Operating revenues	1,083	677	3,140	2,371
Gas distribution operations | SOUTHERN Co GAS
Segment Reporting Information [Line Items]
Goodwill	4,034		4,034		4,034
Wholesale Gas Services | SOUTHERN Co GAS
Segment Reporting Information [Line Items]
Operating revenues		(110)		188
Gas marketing services | SOUTHERN Co GAS
Segment Reporting Information [Line Items]
Goodwill	981		981		981
Operating Segments | SOUTHERN Co GAS
Segment Reporting Information [Line Items]
Operating revenues	1,080	672	3,133	2,373
Segment net income (loss)	116	(62)	425	332
Total assets	24,170		24,170		23,971
Operating Segments | Electric Utilities
Segment Reporting Information [Line Items]
Operating revenues	6,006	4,407	10,516	8,524
Segment net income (loss)	1,134	547	1,981	1,400
Goodwill	2		2		2
Total assets	105,357		105,357		101,774
Operating Segments | Traditional Electric Operating Companies
Segment Reporting Information [Line Items]
Operating revenues	5,563	4,031	9,778	7,795
Segment net income (loss)	1,036	511	1,811	1,267
Goodwill	0		0		0
Total assets	92,742		92,742		89,051
Operating Segments | SOUTHERN POWER CO
Segment Reporting Information [Line Items]
Operating revenues	899	490	1,438	930
Segment net income (loss)	98	36	170	133
Goodwill	2		2		2
Total assets	13,402		13,402		13,390
Operating Segments | SOUTHERN Co GAS
Segment Reporting Information [Line Items]
Operating revenues	1,083	677	3,140	2,371
Segment net income (loss)	115	(65)	433	333
Goodwill	5,015		5,015		5,015
Total assets	23,618		23,618		23,560
Operating Segments | Gas distribution operations | SOUTHERN Co GAS
Segment Reporting Information [Line Items]
Operating revenues	980	710	2,782	1,910
Segment net income (loss)	92	80	306	263
Total assets	21,183		21,183		20,917
Operating Segments | Gas Pipeline Investments | SOUTHERN Co GAS
Segment Reporting Information [Line Items]
Operating revenues	8	8	16	16
Segment net income (loss)	23	(36)	52	(7)
Total assets	1,433		1,433		1,467
Operating Segments | Wholesale Gas Services | SOUTHERN Co GAS
Segment Reporting Information [Line Items]
Operating revenues	0	(110)	0	188
Segment net income (loss)	0	(112)	0	14
Total assets	0		0		31
Operating Segments | Gas marketing services | SOUTHERN Co GAS
Segment Reporting Information [Line Items]
Operating revenues	92	64	335	259
Segment net income (loss)	1	6	67	62
Total assets	1,554		1,554		1,556
Operating Segments | All Other
Segment Reporting Information [Line Items]
Operating revenues	159	154	283	288
Segment net income (loss)	(137)	(108)	(263)	(216)
Goodwill	263		263		263
Total assets	2,457		2,457		2,975
Operating Segments | All Other | SOUTHERN Co GAS
Segment Reporting Information [Line Items]
Operating revenues	10	11	26	18
Segment net income (loss)	(1)	(3)	8	1
Total assets	11,999		11,999		12,114
Eliminations
Segment Reporting Information [Line Items]
Operating revenues	(42)	(40)	(85)	(75)
Segment net income (loss)	(5)	(2)	(12)	(9)
Goodwill	0		0		0
Total assets	(663)		(663)		(775)
Eliminations | SOUTHERN Co GAS
Segment Reporting Information [Line Items]
Operating revenues	(7)	(6)	(19)	(20)
Segment net income (loss)	0	0	0	0
Total assets	(12,551)		(12,551)		(12,525)
Eliminations | Electric Utilities
Segment Reporting Information [Line Items]
Operating revenues	(456)	(114)	(700)	(201)
Segment net income (loss)	0	$ 0	0	$ 0
Goodwill	0		0		0
Total assets	$ (787)		$ (787)		$ (667)