INCOME TAXES (Details)	6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019
Income Tax Contingency [Line Items]
Effective tax (benefit) rate	9.30%	33.50%
GEORGIA POWER CO
Income Tax Contingency [Line Items]
Effective tax (benefit) rate	4.00%	21.70%
MISSISSIPPI POWER CO
Income Tax Contingency [Line Items]
Effective tax (benefit) rate	10.60%	14.00%
SOUTHERN POWER CO
Income Tax Contingency [Line Items]
Effective tax (benefit) rate	10.50%	(35.50%)
SOUTHERN Co GAS
Income Tax Contingency [Line Items]
Effective tax (benefit) rate	21.50%	18.00%