Contingencies and Regulatory Matters - Nuclear Construction (Details) - GEORGIA POWER CO $ in Millions								6 Months Ended	12 Months Ended				48 Months Ended	102 Months Ended
	Jan. 01, 2021	Jan. 01, 2020	Aug. 31, 2018 USD ($)	Apr. 03, 2018 USD ($)	Feb. 28, 2018 USD ($)	Jan. 11, 2018 USD ($)	Jan. 01, 2016	Jun. 30, 2018 USD ($) subcontractor	Dec. 31, 2019 USD ($)	Dec. 31, 2018 USD ($)	Dec. 31, 2017 USD ($)	Dec. 31, 2009 USD ($) utility MW	Dec. 31, 2022 USD ($)	Jun. 30, 2017 USD ($)	Jun. 01, 2021	Sep. 30, 2017 USD ($)	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
Estimated in-service capital cost												$ 4,418
Financing costs collected, net of tax								$ 1,700
Additional construction capital costs						$ 3,300
Amendment to estimated in-service capital cost						$ 5,680
Retail rate of return on common equity																	10.95%
Customer refund				$ 330
Eligible project costs to be reimbursed								3,460
Plant Vogtle Units 3 And 4
Loss Contingencies [Line Items]
Construction financing costs								1,700
Increase in base project capital cost forecast								700
Estimated project costs								1,100
Increase in expected costs								800
Base project capital cost forecast, monthly								50
Monthly AFUDC								$ 12
Percentage of ownership interest required for voting for continuing construction								90.00%
Public utilities, increase in construction budget								$ 1,000
Extension in project schedule								1 year
Percentage of approval required to change primary construction contractor								90.00%
Percentage of approval required for material amendments								67.00%
Cost settlement agreement revised forecast, net of payments								$ 7,300
Additional construction capital costs					$ 448									$ 4,400
Public utilities, approved return on equity percentage							10.00%
Return on equity reduction, negative impact on earnings											$ 25
Guarantor obligations											1,700
Customer refund											$ 188
Scenario, Forecast | Plant Vogtle Units 3 And 4
Loss Contingencies [Line Items]
Construction financing costs									$ 3,200
Public utilities, approved return on equity percentage	5.30%	8.30%
Monthly reduction of ROE to calculate NCRR tariff															0.10%
Return on equity reduction, negative impact on earnings										$ 100			$ 585
Requested capital construction costs			$ 578
Vogtle Owners | Plant Vogtle Units 3 And 4
Loss Contingencies [Line Items]
Period of notice required in the event letters of credit are not renewed								30 days
FFB Loan
Loss Contingencies [Line Items]
Long-term line of credit								$ 2,600
Conditional borrowing commitment																$ 1,670
Minimum | Plant Vogtle Units 3 And 4
Loss Contingencies [Line Items]
Number of subcontractors | subcontractor								60