REGULATORY MATTERS - GPC Tariffs (Details) - Georgia Power $ in Millions	Dec. 31, 2019 USD ($)
Public Utilities, General Disclosures [Line Items]
Rate increase 2020	$ 342
Rate increase (decrease) 2021	111
Rate increase (decrease) 2022	157
Traditional base
Public Utilities, General Disclosures [Line Items]
Rate increase 2020	0
Rate increase (decrease) 2021	120
Rate increase (decrease) 2022	192
ECCR
Public Utilities, General Disclosures [Line Items]
Rate increase 2020	318
Rate increase (decrease) 2021	2
Rate increase (decrease) 2022	(12)
DSM
Public Utilities, General Disclosures [Line Items]
Rate increase 2020	12
Rate increase (decrease) 2021	(15)
Rate increase (decrease) 2022	(25)
MFF
Public Utilities, General Disclosures [Line Items]
Rate increase 2020	12
Rate increase (decrease) 2021	4
Rate increase (decrease) 2022	$ 2