Revenue from Contracts with Customers and Lease Income - Schedule of Lease Income (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2024	Jun. 30, 2023	Jun. 30, 2024	Jun. 30, 2023
Lessor, Lease, Description [Line Items]
Lease income - interest income on sales-type leases	$ 7	$ 6	$ 14	$ 12
Lease income - operating leases	35	42	71	92
Variable lease income	129	123	201	192
Total lease income	171	171	286	296
ALABAMA POWER CO
Lessor, Lease, Description [Line Items]
Lease income - interest income on sales-type leases	0	0	0	0
Lease income - operating leases	2	11	5	29
Variable lease income	0	0	0	0
Total lease income	2	11	5	29
GEORGIA POWER CO
Lessor, Lease, Description [Line Items]
Lease income - interest income on sales-type leases	0	0	0	0
Lease income - operating leases	9	7	16	14
Variable lease income	0	0	0	0
Total lease income	9	7	16	14
MISSISSIPPI POWER CO
Lessor, Lease, Description [Line Items]
Lease income - interest income on sales-type leases	5	4	9	7
Lease income - operating leases	1	1	2	2
Variable lease income	0	0	0	0
Total lease income	6	5	11	9
SOUTHERN POWER CO
Lessor, Lease, Description [Line Items]
Lease income - interest income on sales-type leases	2	2	5	5
Lease income - operating leases	22	21	43	42
Variable lease income	139	132	218	207
Total lease income	163	155	266	254
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