REGULATORY MATTERS - APC Accounting Orders and Plant Greene County (Details) - USD ($) $ in Millions	Dec. 31, 2022	Dec. 31, 2021	Sep. 30, 2021
Public Utilities, General Disclosures [Line Items]
Other deferred charges and assets	$ 20,148	$ 17,259
Alabama Power
Public Utilities, General Disclosures [Line Items]
Other deferred charges and assets	$ 5,372	4,549
Percent ownership	14.00%
Alabama Power | Software Accounting Order
Public Utilities, General Disclosures [Line Items]
Other deferred charges and assets	$ 46	35
Mississippi Power
Public Utilities, General Disclosures [Line Items]
Other deferred charges and assets	$ 828	$ 877
Mississippi Power | Plant Greene County Units 1 and 2
Public Utilities, General Disclosures [Line Items]
Percent ownership			40.00%