Regulatory Matters - Nuclear Construction (Details) - GEORGIA POWER CO $ in Millions							1 Months Ended		6 Months Ended	12 Months Ended				36 Months Ended
	Jan. 01, 2021	Jan. 01, 2020	Aug. 30, 2019 USD ($)	Feb. 19, 2019 USD ($)	Jan. 11, 2018 USD ($)	Jan. 01, 2016	Dec. 31, 2018 USD ($) appeal	Aug. 31, 2018 USD ($)	Jun. 30, 2019 USD ($)	Dec. 31, 2019 USD ($)	Dec. 31, 2018 USD ($)	Dec. 31, 2012 utility MW	Dec. 31, 2009 USD ($)	Dec. 31, 2022 USD ($)	Dec. 31, 2014	Dec. 31, 2013
Loss Contingencies [Line Items]
Number of construction units approved | utility												2
Electric generating capacity in mega watts under consortium agreement | MW												1,100
Additional construction capital costs					$ 3,300.0
Estimated in-service capital cost													$ 4,418.0
Financing costs collected, net of tax									$ 2,000.0
Increase in NCCR tariff							$ 88.0
Amendment to estimated in-service capital cost					$ 5,680.0
Retail rate of return on common equity																10.95%
Number of appeals | appeal							2
Requested capital construction costs				$ 5,400.0
Deferred approval of expenditures related to administrative claim				$ 51.6
Scenario, Forecast
Loss Contingencies [Line Items]
Requested capital construction costs			$ 1,200.0
FFB Loan
Loss Contingencies [Line Items]
Long-term line of credit									3,460.0
Eligible project costs to be reimbursed									$ 5,130.0
Plant Vogtle Units 3 And 4
Loss Contingencies [Line Items]
Proportionate ownership share									45.70%
Construction financing costs									$ 2,000.0
Base project capital cost forecast, monthly									50.0
Monthly AFUDC									12.0
Percentage of ownership interest required for voting for continuing construction								90.00%							90.00%
Cost settlement agreement revised forecast, net of payments									$ 7,300.0
Public utilities, approved return on equity percentage						10.00%
Public utilities, approved return on equity, monthly percentage decrease									0.10%
Return on equity reduction, negative impact on earnings											$ 100.0
Requested capital construction costs								$ 578.0
Guarantor obligations									$ 1,700.0
Customer refund									$ 188.0
Plant Vogtle Units 3 And 4 | Scenario, Forecast
Loss Contingencies [Line Items]
Construction financing costs										$ 3,100.0
Public utilities, approved return on equity percentage	5.30%	8.30%
Return on equity reduction, negative impact on earnings										$ 70.0				$ 630.0
Plant Vogtle Units 3 And 4 | Vogtle Owners
Loss Contingencies [Line Items]
Period of notice required in the event letters of credit are not renewed									30 days