Segment and Related Information - Schedule of Financial Data for Business Segments (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2024	Jun. 30, 2023	Jun. 30, 2024	Jun. 30, 2023	Dec. 31, 2023
Segment Reporting Information [Line Items]
Operating revenues	$ 6,463	$ 5,748	$ 13,109	$ 12,228
Net income	1,203	838	2,332	1,700
Goodwill	5,161		5,161		$ 5,161
Total assets	141,937		141,937		139,331
Credit on plant vogtle units 3 and 4	21	0	21	0
SOUTHERN POWER CO
Segment Reporting Information [Line Items]
Operating revenues	524	525	997	1,033
Net income	86	85	182	187
Total assets	12,764		12,764		12,761
SOUTHERN POWER CO | Disposal Group, Disposed of by Sale | Spare Parts
Segment Reporting Information [Line Items]
Gain (loss) on sale			16
Gain (loss) on sale, after tax			12
SOUTHERN Co GAS
Segment Reporting Information [Line Items]
Operating revenues	831	852	2,538	2,728
Net income	108	85	517	393
Goodwill	5,015		5,015		5,015
Total assets	25,055		25,055		25,083
Nicor Gas
Segment Reporting Information [Line Items]
Pre-tax charge to income			38
After-tax charge to income			28
GEORGIA POWER CO
Segment Reporting Information [Line Items]
Operating revenues	2,875	2,391	5,273	4,567
Total assets	58,795		58,795		56,817
Credit on plant vogtle units 3 and 4	21	0	21	0
After tax credit on plant vogtle units 3 and 4	16
Electric Utilities
Segment Reporting Information [Line Items]
Operating revenues	5,456	4,764	10,271	9,247
SOUTHERN Co GAS
Segment Reporting Information [Line Items]
Operating revenues	831	852	2,538	2,728
Gas distribution operations | SOUTHERN Co GAS
Segment Reporting Information [Line Items]
Goodwill	4,034		4,034		4,034
Operating Segments | SOUTHERN Co GAS
Segment Reporting Information [Line Items]
Operating revenues	827	847	2,533	2,719
Net income	111	86	508	387
Total assets	26,199		26,199		26,055
Operating Segments | Electric Utilities
Segment Reporting Information [Line Items]
Operating revenues	5,456	4,764	10,271	9,247
Net income	1,278	908	2,194	1,620
Goodwill	2		2		2
Total assets	114,706		114,706		112,645
Operating Segments | Traditional Electric Operating Companies
Segment Reporting Information [Line Items]
Operating revenues	5,025	4,359	9,463	8,472
Net income	1,192	823	2,012	1,433
Goodwill	0		0		0
Total assets	102,528		102,528		100,429
Operating Segments | SOUTHERN POWER CO
Segment Reporting Information [Line Items]
Operating revenues	524	525	997	1,033
Net income	86	85	182	187
Goodwill	2		2		2
Total assets	12,764		12,764		12,761
Operating Segments | SOUTHERN Co GAS
Segment Reporting Information [Line Items]
Operating revenues	831	852	2,538	2,728
Net income	108	85	517	393
Goodwill	5,015		5,015		5,015
Total assets	25,055		25,055		25,083
Operating Segments | All Other
Segment Reporting Information [Line Items]
Operating revenues	222	180	383	346
Net income	(181)	(157)	(368)	(311)
Goodwill	144		144		144
Total assets	2,828		2,828		2,446
Operating Segments | All Other | SOUTHERN Co GAS
Segment Reporting Information [Line Items]
Operating revenues	7	9	13	22
Net income	(3)	(1)	9	6
Total assets	9,795		9,795		9,675
Operating Segments | Gas distribution operations | SOUTHERN Co GAS
Segment Reporting Information [Line Items]
Operating revenues	749	764	2,212	2,383
Net income	80	60	382	281
Total assets	23,025		23,025		22,906
Eliminations
Segment Reporting Information [Line Items]
Operating revenues	(46)	(48)	(83)	(93)
Net income	(2)	2	(11)	(2)
Goodwill	0		0		0
Total assets	(652)		(652)		(843)
Eliminations | SOUTHERN Co GAS
Segment Reporting Information [Line Items]
Operating revenues	(3)	(4)	(8)	(13)
Net income	0	0	0	0
Total assets	(10,939)		(10,939)		(10,647)
Eliminations | Electric Utilities
Segment Reporting Information [Line Items]
Operating revenues	(93)	(120)	(189)	(258)
Net income	0	$ 0	0	$ 0
Goodwill	0		0		0
Total assets	$ (586)		$ (586)		$ (545)