Contingencies and Regulatory Matters - Nuclear Construction (Details) - GEORGIA POWER CO							1 Months Ended	3 Months Ended	9 Months Ended	12 Months Ended				48 Months Ended	108 Months Ended
	Jan. 01, 2021	Jan. 01, 2020	Nov. 09, 2018 USD ($)	Aug. 31, 2018 USD ($)	Jan. 11, 2018 USD ($)	Jan. 01, 2016	Sep. 30, 2018 USD ($) subcontractor	Jun. 30, 2018 USD ($)	Sep. 30, 2018 USD ($) subcontractor MW	Dec. 31, 2019 USD ($)	Dec. 31, 2018 USD ($)	Dec. 31, 2017 USD ($) report	Dec. 31, 2009 USD ($) utility MW	Dec. 31, 2022 USD ($)	Dec. 31, 2017 USD ($)	Jun. 01, 2021	Mar. 08, 2018 appeal	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
Additional construction capital costs					$ 3,300,000,000
Estimated in-service capital cost													$ 4,418,000,000
Financing costs collected, net of tax									$ 1,800,000,000
Amendment to estimated in-service capital cost					$ 5,680,000,000
Retail rate of return on common equity																			10.95%
Eligible project costs to be reimbursed									3,460,000,000
Scenario, Forecast
Loss Contingencies [Line Items]
Increase in NCCR tariff			$ 90,000,000
FFB Loan
Loss Contingencies [Line Items]
Long-term line of credit							$ 2,600,000,000		2,600,000,000
Conditional borrowing commitment																		$ 1,670,000,000
Plant Vogtle Units 3 And 4
Loss Contingencies [Line Items]
Construction financing costs									1,800,000,000
Increase in base project capital cost forecast								$ 700,000,000
Estimated project costs								1,100,000,000
Increase in expected costs								$ 800,000,000
Base project capital cost forecast, monthly									50,000,000
Monthly AFUDC									12,000,000
Percentage of ownership interest required for voting for continuing construction				90.00%
Project capital cost forecast							$ 8,400,000,000		8,400,000,000
Additional construction capital costs															$ 4,900,000,000
Construction costs, threshold									$ 2,100,000,000
Percentage of remaining share of construction costs to pay									100.00%
Percentage of cost savings									60.70%
Increase costs amount									$ 100,000
Percentage of approval required to change primary construction contractor							90.00%		90.00%
Percent disallowed for recovery									6.00%
Disallowed for recovery reporting period									6 months
Extension in project schedule							1 year
Percentage of approval required for material amendments							67.00%		67.00%
Voted in favor period									30 days
Ownership interests voted in favor									50.00%
Share of plants (mw) | MW									206
Aggregate purchase price not to exceed									$ 300,000,000
Funding for project									250,000,000
Cost settlement agreement revised forecast, net of payments							$ 7,300,000,000		7,300,000,000
Public utilities, approved return on equity percentage						10.00%
Return on equity reduction, negative impact on earnings												$ 25,000,000
Number Of Appeals | appeal																	2
Number of VCM reports approved | report												18
Guarantor obligations							$ 1,700,000,000		1,700,000,000
Customer refund									$ 188,000,000
Requested capital construction costs				$ 578,000,000
Plant Vogtle Units 3 And 4 | Scenario, Forecast
Loss Contingencies [Line Items]
Construction financing costs										$ 3,200,000,000
Public utilities, approved return on equity percentage	5.30%	8.30%
Approved return on equity, monthly percentage decrease																0.10%
Return on equity reduction, negative impact on earnings											$ 100,000,000			$ 680,000,000
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
Percentage of cost savings									39.30%
Plant Vogtle Units 3 And 4 | Minimum
Loss Contingencies [Line Items]
Number of subcontractors | subcontractor							60		60
Category I | Plant Vogtle Units 3 And 4
Loss Contingencies [Line Items]
Additional construction capital costs									$ 800,000,000
Category II | Plant Vogtle Units 3 And 4
Loss Contingencies [Line Items]
Percentage of construction costs responsible to pay									55.70%
Category II | Plant Vogtle Units 3 And 4 | Vogtle Owners
Loss Contingencies [Line Items]
Percentage of construction costs responsible to pay									44.30%
Category II | Plant Vogtle Units 3 And 4 | Minimum
Loss Contingencies [Line Items]
Additional construction capital costs									$ 80,000,000
Construction costs, threshold									800,000,000
Category II | Plant Vogtle Units 3 And 4 | Maximum
Loss Contingencies [Line Items]
Construction costs, threshold									$ 1,600,000,000
Category III | Plant Vogtle Units 3 And 4
Loss Contingencies [Line Items]
Percentage of construction costs responsible to pay									65.70%
Category III | Plant Vogtle Units 3 And 4 | Vogtle Owners
Loss Contingencies [Line Items]
Percentage of construction costs responsible to pay									34.30%
Category III | Plant Vogtle Units 3 And 4 | Minimum
Loss Contingencies [Line Items]
Additional construction capital costs									$ 100,000,000
Construction costs, threshold									1,600,000,000
Category III | Plant Vogtle Units 3 And 4 | Maximum
Loss Contingencies [Line Items]
Construction costs, threshold									$ 2,100,000,000