Income Taxes - Narrative (Details) - USD ($) $ in Billions	6 Months Ended
	Jun. 30, 2022	Jun. 30, 2021	Dec. 31, 2021
Income Tax Contingency [Line Items]
Effective tax (benefit) rate	18.70%	10.70%
ITC and PTC carryforwards
Income Tax Contingency [Line Items]
Deferred tax assets	$ 0.9		$ 1.2
GEORGIA POWER CO
Income Tax Contingency [Line Items]
Effective tax (benefit) rate	16.40%	(6.90%)
MISSISSIPPI POWER CO
Income Tax Contingency [Line Items]
Effective tax (benefit) rate	18.80%	12.60%
SOUTHERN POWER CO
Income Tax Contingency [Line Items]
Effective tax (benefit) rate	11.20%	(12.80%)