Revenue from Contracts with Customers and Lease Income - Schedule of Lease Income (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2022	Jun. 30, 2021	Jun. 30, 2022	Jun. 30, 2021
Lessor, Lease, Description [Line Items]
Lease income - interest income on sales-type leases	$ 7	$ 4	$ 13	$ 7
Lease income - operating leases	52	56	105	112
Variable lease income	129	128	211	212
Total lease income	188	188	329	331
ALABAMA POWER CO
Lessor, Lease, Description [Line Items]
Lease income - interest income on sales-type leases	0	0	0	0
Lease income - operating leases	19	21	39	41
Variable lease income	0	(1)	0	0
Total lease income	19	20	39	41
GEORGIA POWER CO
Lessor, Lease, Description [Line Items]
Lease income - interest income on sales-type leases	0	0	0	0
Lease income - operating leases	8	10	16	21
Variable lease income	0	0	0	0
Total lease income	8	10	16	21
MISSISSIPPI POWER CO
Lessor, Lease, Description [Line Items]
Lease income - interest income on sales-type leases	4	4	8	7
Lease income - operating leases	0	0	1	1
Variable lease income	0	0	0	0
Total lease income	4	4	9	8
SOUTHERN POWER CO
Lessor, Lease, Description [Line Items]
Lease income - interest income on sales-type leases	3	0	5	0
Lease income - operating leases	21	21	42	42
Variable lease income	138	138	227	228
Total lease income	162	159	274	270
SOUTHERN Co GAS
Lessor, Lease, Description [Line Items]
Lease income - interest income on sales-type leases	0	0	0	0
Lease income - operating leases	9	9	18	17
Variable lease income	0	0	0	0
Total lease income	$ 9	$ 9	$ 18	$ 17