Revenue from Contracts with Customers and Lease Income - Schedule of Lease Income (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2023	Jun. 30, 2022	Jun. 30, 2023	Jun. 30, 2022
Lessor, Lease, Description [Line Items]
Lease income - interest income on sales-type leases	$ 6	$ 7	$ 12	$ 13
Lease income - operating leases	42	52	92	105
Variable lease income	123	129	192	211
Total lease income	171	188	296	329
ALABAMA POWER CO
Lessor, Lease, Description [Line Items]
Lease income - interest income on sales-type leases	0	0	0	0
Lease income - operating leases	11	19	29	39
Variable lease income	0	0	0	0
Total lease income	11	19	29	39
GEORGIA POWER CO
Lessor, Lease, Description [Line Items]
Lease income - interest income on sales-type leases	0	0	0	0
Lease income - operating leases	7	8	14	16
Variable lease income	0	0	0	0
Total lease income	7	8	14	16
MISSISSIPPI POWER CO
Lessor, Lease, Description [Line Items]
Lease income - interest income on sales-type leases	4	4	7	8
Lease income - operating leases	1	0	2	1
Variable lease income	0	0	0	0
Total lease income	5	4	9	9
SOUTHERN POWER CO
Lessor, Lease, Description [Line Items]
Lease income - interest income on sales-type leases	2	3	5	5
Lease income - operating leases	21	21	42	42
Variable lease income	132	138	207	227
Total lease income	155	162	254	274
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	18
Variable lease income	0	0	0	0
Total lease income	$ 9	$ 9	$ 18	$ 18