Contingencies and Regulatory Matters - Georgia Power (Details) $ in Millions		1 Months Ended			3 Months Ended		12 Months Ended
	Apr. 03, 2018 USD ($)	Feb. 29, 2020 USD ($)	Jun. 30, 2019 USD ($)	Oct. 31, 2018 USD ($)	Mar. 31, 2018 USD ($)	Mar. 31, 2017 USD ($)	Dec. 31, 2019	Dec. 31, 2017 USD ($)
Loss Contingencies [Line Items]
Effective tax rate					10.80%	32.10%
Deferred income tax expense (benefit)					$ 34	$ 161
GEORGIA POWER CO
Loss Contingencies [Line Items]
Deferred income tax expense (benefit)					(38)	$ 71
Under recovered fuel balance, threshold for interim fuel rider					200
GEORGIA POWER CO | Other current liabilities
Loss Contingencies [Line Items]
Over recovered fuel balance					$ 156			$ 165
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%
Subsequent Event | GEORGIA POWER CO
Loss Contingencies [Line Items]
Customer refund	$ 330
Deferred income tax expense (benefit)	(700)
Customer refund liability in absence of base rate case	$ 185
Subsequent Event | GEORGIA POWER CO | Maximum
Loss Contingencies [Line Items]
Retail regulatory equity ratio	0.55
Subsequent Event | State and Local Jurisdiction | GEORGIA POWER CO
Loss Contingencies [Line Items]
Effective tax rate	6.00%