ASSET RETIREMENT OBLIGATIONS - Accumulated Provisions for the External Decommissioning Trust Funds (Details) - External decommissioning trust funds - USD ($) $ in Millions	Dec. 31, 2023	Dec. 31, 2022
Georgia Power
Public Utilities, General Disclosures [Line Items]
Accumulated provisions for decommissioning	$ 1,163	$ 1,018
Plant Farley | Alabama Power
Public Utilities, General Disclosures [Line Items]
Accumulated provisions for decommissioning	1,259	1,125
Plant Hatch | Georgia Power
Public Utilities, General Disclosures [Line Items]
Accumulated provisions for decommissioning	705	628
Plant Vogtle Units 1 and 2 | Georgia Power
Public Utilities, General Disclosures [Line Items]
Accumulated provisions for decommissioning	434	382
Plant Vogtle Units 3 and 4 | Georgia Power
Public Utilities, General Disclosures [Line Items]
Accumulated provisions for decommissioning	$ 24	$ 8