PROPERTY, PLANT, AND EQUIPMENT - Assets Acquired Under a Capital Lease (Details) $ in Millions	Dec. 31, 2018 USD ($)
Capital Leased Assets [Line Items]
Less: Accumulated amortization	$ (75)
Balance, net of amortization	191
Office buildings
Capital Leased Assets [Line Items]
Capital leased assets, gross	216
PPAs
Capital Leased Assets [Line Items]
Capital leased assets, gross	0
Computer-related equipment
Capital Leased Assets [Line Items]
Capital leased assets, gross	43
Gas pipeline
Capital Leased Assets [Line Items]
Capital leased assets, gross	7
Georgia Power
Capital Leased Assets [Line Items]
Less: Accumulated amortization	(84)
Balance, net of amortization	121
Georgia Power | Office buildings
Capital Leased Assets [Line Items]
Capital leased assets, gross	61
Georgia Power | PPAs
Capital Leased Assets [Line Items]
Capital leased assets, gross	144
Georgia Power | Computer-related equipment
Capital Leased Assets [Line Items]
Capital leased assets, gross	0
Georgia Power | Gas pipeline
Capital Leased Assets [Line Items]
Capital leased assets, gross	$ 0