LEASES - Maturities of Lease Liabilities (Details) - USD ($) $ in Millions	Dec. 31, 2022	Dec. 31, 2021
Operating leases:
2023	$ 248
2024	201
2025	181
2026	159
2027	143
Thereafter	1,497
Total	2,429
Less: Present value discount	844
Operating lease obligations	1,585	$ 1,754
Finance leases:
2023	33
2024	22
2025	26
2026	26
2027	26
Thereafter	345
Total	478
Less: Present value discount	164
Finance lease obligations	314	215
Alabama Power
Operating leases:
2023	12
2024	10
2025	9
2026	6
2027	5
Thereafter	64
Total	106
Less: Present value discount	30
Operating lease obligations	76	121
Finance leases:
2023	2
2024	1
2025	1
2026	1
2027	0
Thereafter	0
Total	5
Less: Present value discount	0
Finance lease obligations	5	4
Georgia Power
Operating leases:
2023	191
2024	165
2025	138
2026	135
2027	135
Thereafter	440
Total	1,204
Less: Present value discount	202
Operating lease obligations	1,002	1,155
Finance leases:
2023	35
2024	27
2025	35
2026	36
2027	36
Thereafter	187
Total	356
Less: Present value discount	118
Finance lease obligations	238	136
Mississippi Power
Operating leases:
2023	4
2024	2
2025	2
2026	1
2027	0
Thereafter	1
Total	10
Less: Present value discount	1
Operating lease obligations	9	10
Finance leases:
2023	2
2024	2
2025	2
2026	2
2027	2
Thereafter	10
Total	20
Less: Present value discount	3
Finance lease obligations	17	18
Southern Power
Operating leases:
2023	36
2024	28
2025	28
2026	28
2027	29
Thereafter	1,009
Total	1,158
Less: Present value discount	616
Operating lease obligations	542	525
Finance leases:
2023	0
2024	0
2025	0
2026	0
2027	0
Thereafter	0
Total	0
Less: Present value discount	0
Finance lease obligations	0	0
Southern Company Gas
Operating leases:
2023	11
2024	11
2025	11
2026	8
2027	3
Thereafter	31
Total	75
Less: Present value discount	15
Operating lease obligations	60	70
Finance leases:
2023	0
2024	0
2025	0
2026	0
2027	0
Thereafter	0
Total	0
Less: Present value discount	0
Finance lease obligations	$ 0	$ 0