Financing and Leases - Schedule of Credit Arrangements (Details)	Mar. 31, 2023 USD ($)
Line of Credit Facility [Line Items]
Expires, 2023	$ 280,000,000
Expires, 2024	700,000,000
Expires, 2025	125,000,000
Expires, 2026	6,550,000,000
Total	7,655,000,000
Unused	7,564,000,000
Expires within One Year	280,000,000
Southern Company parent
Line of Credit Facility [Line Items]
Expires, 2023	0
Expires, 2024	0
Expires, 2025	0
Expires, 2026	2,000,000,000
Total	2,000,000,000
Unused	1,998,000,000
Expires within One Year	0
ALABAMA POWER CO
Line of Credit Facility [Line Items]
Expires, 2023	0
Expires, 2024	550,000,000
Expires, 2025	0
Expires, 2026	700,000,000
Total	1,250,000,000
Unused	1,250,000,000
Expires within One Year	0
GEORGIA POWER CO
Line of Credit Facility [Line Items]
Expires, 2023	0
Expires, 2024	0
Expires, 2025	0
Expires, 2026	1,750,000,000
Total	1,750,000,000
Unused	1,726,000,000
Expires within One Year	0
MISSISSIPPI POWER CO
Line of Credit Facility [Line Items]
Expires, 2023	0
Expires, 2024	150,000,000
Expires, 2025	125,000,000
Expires, 2026	0
Total	275,000,000
Unused	225,000,000
Expires within One Year	0
SOUTHERN POWER CO
Line of Credit Facility [Line Items]
Expires, 2023	0
Expires, 2024	0
Expires, 2025	0
Expires, 2026	600,000,000
Total	600,000,000
Unused	587,000,000
Expires within One Year	0
SOUTHERN POWER CO | Continuing Letter of Credit Facility A
Line of Credit Facility [Line Items]
Expires, 2025	75,000,000
Expires, 2026	100,000,000
Unused	9,000,000
SOUTHERN POWER CO | Continuing Letter of Credit Facility B
Line of Credit Facility [Line Items]
Unused	16,000,000
SOUTHERN Co GAS
Line of Credit Facility [Line Items]
Expires, 2023	250,000,000
Expires, 2024	0
Expires, 2025	0
Expires, 2026	1,500,000,000
Total	1,750,000,000
Unused	1,748,000,000
Expires within One Year	250,000,000
SEGCO
Line of Credit Facility [Line Items]
Expires, 2023	30,000,000
Expires, 2024	0
Expires, 2025	0
Expires, 2026	0
Total	30,000,000
Unused	30,000,000
Expires within One Year	30,000,000
Southern Company Gas Capital
Line of Credit Facility [Line Items]
Expires, 2027	800,000,000
Nicor Gas
Line of Credit Facility [Line Items]
Expires, 2027	$ 700,000,000