Segment and Related Information - Schedule of Financial Data for Business Segments (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2023	Jun. 30, 2022	Jun. 30, 2023	Jun. 30, 2022	Dec. 31, 2022
Segment Reporting Information [Line Items]
Operating revenues	$ 5,748	$ 7,206	$ 12,228	$ 13,854
Net income	838	1,107	1,700	2,139
Goodwill	5,161		5,161		$ 5,161
Total assets	137,116		137,116		134,891
SOUTHERN POWER CO
Segment Reporting Information [Line Items]
Operating revenues	525	899	1,033	1,438
Total assets					13,081
SOUTHERN POWER CO | Disposal Group, Disposed of by Sale | Spare Parts
Segment Reporting Information [Line Items]
Gain on sale			16
Gain on sale, after tax			12
SOUTHERN Co GAS
Segment Reporting Information [Line Items]
Operating revenues	852	1,083	2,728	3,140
Net income	85	115	393	433
Goodwill	5,015		5,015		5,015
Total assets	24,331		24,331		24,621
GEORGIA POWER CO
Segment Reporting Information [Line Items]
Operating revenues	2,391	3,121	4,567	5,328
Total assets	55,001		55,001		53,163
GEORGIA POWER CO | Disposal Group, Disposed of by Sale | Spare Parts
Segment Reporting Information [Line Items]
Gain on sale			52
Gain on sale, after tax			39
Electric Utilities
Segment Reporting Information [Line Items]
Operating revenues	4,764	6,006	9,247	10,516
SOUTHERN Co GAS
Segment Reporting Information [Line Items]
Operating revenues	852	1,083	2,728	3,140
Gas distribution operations | SOUTHERN Co GAS
Segment Reporting Information [Line Items]
Goodwill	4,034		4,034		4,034
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	847	1,080	2,719	3,133
Net income	86	116	387	425
Total assets	25,460		25,460		25,233
Operating Segments | Electric Utilities
Segment Reporting Information [Line Items]
Operating revenues	4,764	6,006	9,247	10,516
Net income	908	1,134	1,620	1,981
Goodwill	2		2		2
Total assets	110,208		110,208		108,283
Operating Segments | Traditional Electric Operating Companies
Segment Reporting Information [Line Items]
Operating revenues	4,359	5,563	8,472	9,778
Net income	823	1,036	1,433	1,811
Goodwill	0		0		0
Total assets	97,751		97,751		95,861
Operating Segments | SOUTHERN POWER CO
Segment Reporting Information [Line Items]
Operating revenues	525	899	1,033	1,438
Net income	85	98	187	170
Goodwill	2		2		2
Total assets	13,046		13,046		13,081
Operating Segments | SOUTHERN Co GAS
Segment Reporting Information [Line Items]
Operating revenues	852	1,083	2,728	3,140
Net income	85	115	393	433
Goodwill	5,015		5,015		5,015
Total assets	24,331		24,331		24,621
Operating Segments | Gas distribution operations | SOUTHERN Co GAS
Segment Reporting Information [Line Items]
Operating revenues	764	980	2,383	2,782
Net income	60	92	281	306
Total assets	22,366		22,366		22,040
Operating Segments | Gas Pipeline Investments | SOUTHERN Co GAS
Segment Reporting Information [Line Items]
Operating revenues	8	8	16	16
Net income	19	23	50	52
Total assets	1,552		1,552		1,577
Operating Segments | Gas marketing services | SOUTHERN Co GAS
Segment Reporting Information [Line Items]
Operating revenues	75	92	320	335
Net income	7	1	56	67
Total assets	1,542		1,542		1,616
Operating Segments | All Other
Segment Reporting Information [Line Items]
Operating revenues	180	159	346	283
Net income	(157)	(137)	(311)	(263)
Goodwill	144		144		144
Total assets	3,523		3,523		2,665
Operating Segments | All Other | SOUTHERN Co GAS
Segment Reporting Information [Line Items]
Operating revenues	9	10	22	26
Net income	(1)	(1)	6	8
Total assets	9,606		9,606		8,943
Eliminations
Segment Reporting Information [Line Items]
Operating revenues	(48)	(42)	(93)	(85)
Net income	2	(5)	(2)	(12)
Goodwill	0		0		0
Total assets	(946)		(946)		(678)
Eliminations | SOUTHERN Co GAS
Segment Reporting Information [Line Items]
Operating revenues	(4)	(7)	(13)	(19)
Net income	0	0	0	0
Total assets	(10,735)		(10,735)		(9,555)
Eliminations | Electric Utilities
Segment Reporting Information [Line Items]
Operating revenues	(120)	(456)	(258)	(700)
Net income	0	$ 0	0	$ 0
Goodwill	0		0		0
Total assets	$ (589)		$ (589)		$ (659)