Contingencies and Regulatory Matters - Georgia Power (Details) $ in Millions		1 Months Ended			6 Months Ended		12 Months Ended
	Apr. 03, 2018 USD ($)	Feb. 29, 2020 USD ($)	Jun. 30, 2019 USD ($)	Oct. 31, 2018 USD ($)	Jun. 30, 2018 USD ($)	Jun. 30, 2017 USD ($)	Dec. 31, 2019	Dec. 31, 2017 USD ($)
Loss Contingencies [Line Items]
Effective tax rate					(3.20%)	(28.60%)
Deferred income tax expense (benefit)					$ (338)	$ (270)
GEORGIA POWER CO
Loss Contingencies [Line Items]
Customer refund	$ 330
Effective tax rate					(53.50%)	36.60%
Deferred income tax expense (benefit)	(700)				$ (256)	$ 159
Customer refund liability in absence of base rate case	$ 185
Under recovered fuel balance, threshold for interim fuel rider					200
GEORGIA POWER CO | Maximum
Loss Contingencies [Line Items]
Retail regulatory equity ratio	0.55
GEORGIA POWER CO | Other current liabilities
Loss Contingencies [Line Items]
Over (under) recovered fuel balance					$ (159)			$ (165)
State and Local Jurisdiction | GEORGIA POWER CO
Loss Contingencies [Line Items]
Effective tax rate	6.00%
Scenario, Forecast | GEORGIA POWER CO
Loss Contingencies [Line Items]
Customer refundable fees, refund payments		$ 103	$ 96	$ 131
Scenario, Forecast | State and Local Jurisdiction | GEORGIA POWER CO
Loss Contingencies [Line Items]
Effective tax rate							5.75%