INCOME TAXES - Current and Deferred Income Tax Provisions (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Federal —
Current	$ 54	$ 10	$ 50
Deferred	299	455	36
Total federal taxes	353	465	86
State —
Current	41	27	(25)
Deferred	102	303	206
Total state taxes	143	330	181
Income taxes	496	795	267
Alabama Power
Federal —
Current	242	54	104
Deferred	(257)	259	172
Total federal taxes	(15)	313	276
State —
Current	82	14	23
Deferred	14	96	73
Total state taxes	96	110	96
Income taxes	81	423	372
Georgia Power
Federal —
Current	205	38	311
Deferred	195	152	(449)
Total federal taxes	400	190	(138)
State —
Current	37	(21)	71
Deferred	11	201	(101)
Total state taxes	48	180	(30)
Income taxes	448	370	(168)
Mississippi Power
Federal —
Current	49	42	25
Deferred	(26)	(16)	(15)
Total federal taxes	23	26	10
State —
Current	1	0	0
Deferred	12	11	11
Total state taxes	13	11	11
Income taxes	36	37	21
Southern Power
Federal —
Current	(320)	(43)	(340)
Deferred	334	56	343
Total federal taxes	14	13	3
State —
Current	(1)	2	(16)
Deferred	(1)	5	0
Total state taxes	(2)	7	(16)
Income taxes	12	20	(13)
Southern Company Gas
Federal —
Current	62	122	85
Deferred	68	(3)	35
Total federal taxes	130	119	120
State —
Current	24	42	(68)
Deferred	57	19	223
Total state taxes	81	61	155
Income taxes	$ 211	$ 180	$ 275