INCOME TAXES - Current and Deferred Income Tax Provisions (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Federal —
Current	$ 10	$ 50	$ 199
Deferred	455	36	70
Total federal taxes	465	86	269
State —
Current	27	(25)	100
Deferred	303	206	24
Total state taxes	330	181	124
Income taxes	795	267	393
Alabama Power
Federal —
Current	54	104	198
Deferred	259	172	44
Total federal taxes	313	276	242
State —
Current	14	23	61
Deferred	96	73	34
Total state taxes	110	96	95
Income taxes	423	372	337
Georgia Power
Federal —
Current	38	311	365
Deferred	152	(449)	(224)
Total federal taxes	190	(138)	141
State —
Current	(21)	71	60
Deferred	201	(101)	(49)
Total state taxes	180	(30)	11
Income taxes	370	(168)	152
Mississippi Power
Federal —
Current	42	25	18
Deferred	(16)	(15)	(14)
Total federal taxes	26	10	4
State —
Current	0	0	0
Deferred	11	11	10
Total state taxes	11	11	10
Income taxes	37	21	14
Southern Power
Federal —
Current	(43)	(340)	(303)
Deferred	56	343	299
Total federal taxes	13	3	(4)
State —
Current	2	(16)	(4)
Deferred	5	0	11
Total state taxes	7	(16)	7
Income taxes	20	(13)	3
Southern Company Gas
Federal —
Current	122	85	82
Deferred	(3)	35	53
Total federal taxes	119	120	135
State —
Current	42	(68)	35
Deferred	19	223	3
Total state taxes	61	155	38
Income taxes	$ 180	$ 275	$ 173