LEASES - Additional Information (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Lessee, Lease, Description [Line Items]
Operating lease obligations	$ 1,585	$ 1,754
Transfer of construction work in progress to lease receivables		210
Communication towers
Lessee, Lease, Description [Line Items]
Lessee, renewal period	20 years
Maximum | Real estate
Lessee, Lease, Description [Line Items]
Remaining terms	23 years
Maximum | Land
Lessee, Lease, Description [Line Items]
Lessee, lease term	44 years
Maximum | Communication towers
Lessee, Lease, Description [Line Items]
Lessee, lease term	10 years
Maximum | Fuel cells
Lessee, Lease, Description [Line Items]
Lessor, lease term, operating lease	11 years
Alabama Power
Lessee, Lease, Description [Line Items]
Operating lease obligations	$ 76	121
Alabama Power | Maximum | Electric generating units
Lessee, Lease, Description [Line Items]
Operating lease remaining lease term	17 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	$ 1,002	1,155
Variable lease, payment	45	41	$ 39
Georgia Power | Purchased power, affiliates
Lessee, Lease, Description [Line Items]
Variable lease, payment	21	20	20
Mississippi Power
Lessee, Lease, Description [Line Items]
Operating lease obligations	$ 9	10
Transfer of construction work in progress to lease receivables		39	26
Sales-type lease, lease receivable		39	26
Mississippi Power | Maximum | Electric generating units
Lessee, Lease, Description [Line Items]
Lessor, sales-type lease, term of contract	16 years
Southern Power
Lessee, Lease, Description [Line Items]
Operating lease obligations	$ 542	$ 525
Lessor, sales-type lease, term of contract		20 years
Sales-type lease, lease receivable		$ 210
Loss on sales-type leases	1	40	$ 0
Net investment in sales-type lease, long-term portion	$ 154	161
Southern Power | Maximum | Electric generating units
Lessee, Lease, Description [Line Items]
Lessor, lease term, operating lease	24 years
Lessor, sales-type lease, term of contract	19 years
Southern Company Gas
Lessee, Lease, Description [Line Items]
Operating lease obligations	$ 60	70
Southern Company Gas | Maximum
Lessee, Lease, Description [Line Items]
Lessor, remaining term	20 years
Affiliate | Georgia Power | Electric generating units
Lessee, Lease, Description [Line Items]
Operating lease obligations	$ 461	$ 521
Traditional Electric Operating Companies | Maximum | Outdoor lighting
Lessee, Lease, Description [Line Items]
Lessor, lease term, operating lease	7 years