LEASES - Additional Information (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Lessee, Lease, Description [Line Items]
Operating lease obligations	$ 1,490	$ 1,585
Transfer of construction work in progress to lease receivables			$ 210
Maximum | Real estate
Lessee, Lease, Description [Line Items]
Remaining terms	27 years
Maximum | Land
Lessee, Lease, Description [Line Items]
Lessee, lease term	44 years
Maximum | Communication towers
Lessee, Lease, Description [Line Items]
Lessee, lease term	17 years
Maximum | Fuel cells
Lessee, Lease, Description [Line Items]
Lessor, lease term, operating lease	10 years
Alabama Power
Lessee, Lease, Description [Line Items]
Operating lease obligations	$ 93	76
Alabama Power | Maximum | Electric generating units
Lessee, Lease, Description [Line Items]
Operating lease remaining lease term	16 years
Alabama Power | Minimum | Electric generating units
Lessee, Lease, Description [Line Items]
Operating lease remaining lease term	1 year
Georgia Power
Lessee, Lease, Description [Line Items]
Operating lease obligations	$ 875	1,002
Variable lease, payment	42	45	41
Georgia Power | Purchased power, affiliates
Lessee, Lease, Description [Line Items]
Variable lease, payment	21	21	20
Mississippi Power
Lessee, Lease, Description [Line Items]
Operating lease obligations	$ 9	9
Transfer of construction work in progress to lease receivables			39
Sales-type lease, lease receivable			$ 39
Mississippi Power | Maximum | Electric generating units
Lessee, Lease, Description [Line Items]
Lessor, sales-type lease, term of contract	15 years
Southern Power
Lessee, Lease, Description [Line Items]
Operating lease obligations	$ 546	542
Lessor, sales-type lease, term of contract			20 years
Sales-type lease, lease receivable			$ 210
Loss on sales-type leases	$ 0	1	$ 40
Southern Power | Maximum | Electric generating units
Lessee, Lease, Description [Line Items]
Lessor, lease term, operating lease	23 years
Lessor, sales-type lease, term of contract	18 years
Southern Company Gas
Lessee, Lease, Description [Line Items]
Operating lease obligations	$ 51	60
Southern Company Gas | Maximum
Lessee, Lease, Description [Line Items]
Lessor, remaining term	19 years
Affiliate | Georgia Power | Electric generating units
Lessee, Lease, Description [Line Items]
Operating lease obligations	$ 416	$ 461
Traditional Electric Operating Companies | Maximum | Outdoor lighting
Lessee, Lease, Description [Line Items]
Lessor, lease term, operating lease	10 years