SEGMENT AND RELATED INFORMATION - Financial Data for Business Segments (Details) $ in Millions		1 Months Ended			3 Months Ended					6 Months Ended		12 Months Ended
	Jul. 01, 2021 USD ($)	Dec. 31, 2021 USD ($) project	Jul. 31, 2021 USD ($)	Jan. 31, 2020 USD ($)	Dec. 31, 2022 USD ($)	Sep. 30, 2021 USD ($)	Jun. 30, 2021 USD ($)	Dec. 31, 2020 USD ($)	Jun. 30, 2020 USD ($)	Dec. 31, 2021 USD ($)	Dec. 31, 2021 USD ($)	Dec. 31, 2022 USD ($) project	Dec. 31, 2021 USD ($)	Dec. 31, 2020 USD ($)
Segment Reporting Information [Line Items]
Total operating revenues												$ 29,279	$ 23,113	$ 20,375
Depreciation and amortization												3,663	3,565	3,518
Operating income (loss)												5,370	3,698	4,885
Interest income												59	22	37
Earnings from equity method investments												151	76	153
Interest expense												2,022	1,837	1,821
Income taxes (benefit)												795	267	393
Segment net income (loss)												3,524	2,393	3,119
Goodwill		$ 5,280			$ 5,161			$ 5,280		$ 5,280	$ 5,280	5,161	5,280	5,280
Total assets		127,534			134,891			122,935		127,534	127,534	134,891	127,534	122,935
Segment and Related Information (Textual) [Abstract]
Estimated loss on Plant Vogtle Units 3 and 4												183	1,692	325
Gain (loss) on dispositions												42	176	66
Impairment charges												$ 251	2	0
Gain (loss) on termination of leveraged leases		93
Gain (loss) on termination of leveraged leases, after tax		$ 99
Number of international projects subject to leveraged lease terminated | project		2										2
Lease, impairment loss									$ 154			$ 0	7	206
Lease, impairment loss, after tax									$ 74
Southern Company Gas
Segment Reporting Information [Line Items]
Total operating revenues												5,962	4,380	3,434
All Other
Segment and Related Information (Textual) [Abstract]
Lease, impairment loss							$ 7	18					7	206
Lease, impairment loss, after tax							6	14					6	105
Operating Segments | Electric Utilities
Segment Reporting Information [Line Items]
Total operating revenues												22,873	18,300	16,497
Depreciation and amortization												3,029	2,953	2,941
Interest income												47	21	30
Earnings from equity method investments												0	1	0
Interest expense												1,067	968	976
Income taxes (benefit)												848	219	517
Segment net income (loss)												3,672	2,247	3,115
Goodwill		$ 2			2			2		2	2	2	2	2
Total assets		101,774			108,283			98,041		101,774	101,774	108,283	101,774	98,041
Operating Segments | Traditional Electric Operating Companies
Segment Reporting Information [Line Items]
Total operating revenues												20,408	16,614	15,135
Depreciation and amortization												2,513	2,436	2,447
Interest income												44	20	26
Earnings from equity method investments												0	1	0
Interest expense												929	821	825
Income taxes (benefit)												828	232	514
Segment net income (loss)												3,318	1,981	2,877
Goodwill		0			0			0		0	0	0	0	0
Total assets		89,051			95,861			85,486		89,051	89,051	95,861	89,051	85,486
Operating Segments | Southern Power
Segment Reporting Information [Line Items]
Total operating revenues												3,369	2,216	1,733
Depreciation and amortization												516	517	494
Interest income												3	1	4
Earnings from equity method investments												0	0	0
Interest expense												138	147	151
Income taxes (benefit)												20	(13)	3
Segment net income (loss)												354	266	238
Goodwill		2			2			2		2	2	2	2	2
Total assets		13,390			13,081			13,235		13,390	13,390	13,081	13,390	13,235
Operating Segments | Southern Company Gas
Segment Reporting Information [Line Items]
Total operating revenues												5,962	4,380	3,434
Depreciation and amortization												559	536	500
Interest income												3	0	5
Earnings from equity method investments												148	50	141
Interest expense												263	238	231
Income taxes (benefit)												180	275	173
Segment net income (loss)												572	539	590
Goodwill		5,015			5,015			5,015		5,015	5,015	5,015	5,015	5,015
Total assets		23,560			24,621			22,630		23,560	23,560	24,621	23,560	22,630
Operating Segments | All Other
Segment Reporting Information [Line Items]
Total operating revenues												593	582	596
Depreciation and amortization												75	76	77
Interest income												16	4	6
Earnings from equity method investments												3	24	12
Interest expense												694	631	614
Income taxes (benefit)												(233)	(227)	(297)
Segment net income (loss)												(711)	(384)	(592)
Goodwill		263			144			263		263	263	144	263	263
Total assets		2,975			2,665			3,168		2,975	2,975	2,665	2,975	3,168
Intersegment Eliminations
Segment Reporting Information [Line Items]
Total operating revenues												(149)	(149)	(152)
Depreciation and amortization												0	0	0
Interest income												(7)	(3)	(4)
Earnings from equity method investments												0	1	0
Interest expense												(2)	0	0
Income taxes (benefit)												0	0	0
Segment net income (loss)												(9)	(9)	6
Goodwill		0			0			0		0	0	0	0	0
Total assets		(775)			(678)			(904)		(775)	(775)	(678)	(775)	(904)
Intersegment Eliminations | Electric Utilities
Segment Reporting Information [Line Items]
Total operating revenues												(904)	(530)	(371)
Depreciation and amortization												0	0	0
Interest income												0	0	0
Earnings from equity method investments												0	0	0
Interest expense												0	0	0
Income taxes (benefit)												0	0	0
Segment net income (loss)												0	0	0
Goodwill		0			0			0		0	0	0	0	0
Total assets		(667)			(659)			(680)		(667)	(667)	(659)	(667)	(680)
Georgia Power
Segment Reporting Information [Line Items]
Total operating revenues												11,584	9,260	8,309
Depreciation and amortization												1,430	1,371	1,425
Operating income (loss)												2,352	568	1,972
Interest expense												485	421	425
Income taxes (benefit)												370	(168)	152
Total assets		48,461			53,163					48,461	48,461	53,163	48,461
Segment and Related Information (Textual) [Abstract]
Estimated loss on Plant Vogtle Units 3 and 4												183	1,692	325
Georgia Power | Traditional Electric Operating Companies | Plant Vogtle Units 3 and 4
Segment and Related Information (Textual) [Abstract]
Estimated loss on Plant Vogtle Units 3 and 4												183	1,700
Estimated loss on Plant Vogtle Units 3 and 4, net of tax												137	1,300	242
Southern Power
Segment Reporting Information [Line Items]
Total operating revenues												3,369	2,216	1,733
Depreciation and amortization												516	517	494
Operating income (loss)												398	291	342
Interest expense												138	147	151
Income taxes (benefit)												20	(13)	3
Total assets		13,390			13,081					13,390	13,390	13,081	13,390
Segment and Related Information (Textual) [Abstract]
Gain (loss) on dispositions												2	41	39
Southern Power | Wind Generating Facility
Segment and Related Information (Textual) [Abstract]
Gain (loss) on dispositions												37
Gain (loss) on dispositions, after tax												28
Southern Company Gas
Segment Reporting Information [Line Items]
Total operating revenues												5,962	4,380	3,434
Depreciation and amortization												559	536	500
Operating income (loss)												814	1,055	812
Earnings from equity method investments												148	50	141
Interest expense												263	238	231
Income taxes (benefit)												180	275	173
Segment net income (loss)												572	539	590
Goodwill		5,015			5,015					5,015	5,015	5,015	5,015
Total assets		23,560			24,621			22,630		23,560	23,560	24,621	23,560	22,630
Segment and Related Information (Textual) [Abstract]
Gain (loss) on dispositions												4	127	22
Impairment charges												131	0	0
Southern Company Gas | PennEast Pipeline
Segment Reporting Information [Line Items]
Earnings from equity method investments												0	(81)	7
Income taxes (benefit)													7
Segment and Related Information (Textual) [Abstract]
Impairment charges						$ 2	82					84	84
Impairment charges, after tax						$ 2	$ 58					67	67
Southern Company Gas | Operating Segments
Segment Reporting Information [Line Items]
Total operating revenues												5,937	4,374	3,466
Depreciation and amortization												537	505	470
Operating income (loss)												957	1,095	814
Earnings from equity method investments												148	50	141
Interest expense												259	237	228
Income taxes (benefit)												217	213	178
Segment net income (loss)												671	626	592
Total assets		23,971			25,233			23,040		23,971	23,971	25,233	23,971	23,040
Southern Company Gas | Operating Segments | All Other
Segment Reporting Information [Line Items]
Total operating revenues												55	38	36
Depreciation and amortization												22	31	30
Operating income (loss)												(135)	(40)	(7)
Earnings from equity method investments												0	0	0
Interest expense												4	1	3
Income taxes (benefit)												(37)	62	(5)
Segment net income (loss)												(99)	(87)	(2)
Total assets		12,114			8,943			11,336		12,114	12,114	8,943	12,114	11,336
Southern Company Gas | Intersegment Eliminations
Segment Reporting Information [Line Items]
Total operating revenues												(30)	(32)	(68)
Depreciation and amortization												0	0	0
Operating income (loss)												(8)	0	5
Earnings from equity method investments												0	0	0
Interest expense												0	0	0
Income taxes (benefit)												0	0	0
Segment net income (loss)												0	0	0
Total assets		$ (12,525)			(9,555)			$ (11,746)		(12,525)	(12,525)	(9,555)	$ (12,525)	(11,746)
Sequent | Disposal Group, Disposed of by Sale, Not Discontinued Operations | Southern Company Gas
Segment and Related Information (Textual) [Abstract]
Gain (loss) on dispositions	$ 121											121
Gain (loss) on dispositions, after tax	$ 92											92
Deferred tax expense, increase from change in appointment rate			$ 85							$ 85	$ 85	$ 85
Mankato | Disposal Group, Disposed of by Sale, Not Discontinued Operations | Southern Power
Segment and Related Information (Textual) [Abstract]
Gain (loss) on dispositions				$ 39
Gain (loss) on dispositions, after tax				$ 23
Gain on sale														39
Gain on sale, after tax														$ 23
Natural Gas Storage Facilities | Disposal Group, Disposed of by Sale, Not Discontinued Operations | Southern Company Gas
Segment and Related Information (Textual) [Abstract]
Gain (loss) on dispositions					(131)
Gain (loss) on dispositions, after tax					$ (99)