Contingencies and Regulatory Matters - Textual - SO Nuclear Construction (Details)												3 Months Ended	9 Months Ended	12 Months Ended					48 Months Ended		90 Months Ended
	Jan. 01, 2021	Jan. 01, 2020	Feb. 28, 2018 USD ($)	Jan. 30, 2018 USD ($)	Jan. 11, 2018 USD ($)	Dec. 08, 2017 payment	Jun. 09, 2017 USD ($)	Dec. 31, 2016 USD ($)	Dec. 20, 2016 USD ($)	Jan. 01, 2016	Feb. 20, 2014 USD ($)	Sep. 30, 2018 USD ($) installment	Sep. 30, 2017 USD ($)	Dec. 31, 2019 USD ($)	Dec. 31, 2018 USD ($)	Dec. 31, 2017 USD ($)	Dec. 31, 2016 USD ($)	Dec. 31, 2009 USD ($) utility MW	Dec. 31, 2022 USD ($)	Dec. 31, 2020 USD ($)	Jun. 30, 2016 USD ($)	Sep. 28, 2017 USD ($)	Mar. 31, 2016 USD ($)	Dec. 31, 2013	Jan. 01, 2013
Loss Contingencies [Line Items]
Construction work in progress								$ 8,977,000,000								$ 6,904,000,000	$ 8,977,000,000
Line of credit facility, maximum borrowing capacity																8,145,000,000
GEORGIA POWER CO
Loss Contingencies [Line Items]
Number of construction units approved | utility																		2
Electric generating capacity in mega watts under construction agreement | MW																		1,100
Construction work in progress								4,939,000,000								4,613,000,000	4,939,000,000
Line of credit facility, maximum borrowing capacity																1,750,000,000
Maximum guarantee																$ 43,000,000
Retail rate of return on common equity																									10.95%
Return on equity, potential decrease each month percentage																10.00%
Eligible project costs to be reimbursed											$ 3,460,000,000
GEORGIA POWER CO | Plant Vogtle Units 3 And 4
Loss Contingencies [Line Items]
Line of credit facility, maximum borrowing capacity																							$ 920,000,000
Plant Vogtle Units 3 And 4
Loss Contingencies [Line Items]
Maximum guarantee							$ 3,680,000,000.00
Plant Vogtle Units 3 And 4 | GEORGIA POWER CO
Loss Contingencies [Line Items]
Percent ownership																45.70%
Cost settlement agreement revised forecast																$ 8,800,000,000
Project capital cost forecast																7,300,000,000
Construction work in progress																3,300,000,000
Construction financing costs								1,600,000,000
Maximum guarantee							$ 1,700,000,000.0
Number of payments made | payment						3
Ownership interest percentage required for voting for continuing construction													90.00%
Increase (decrease) in construction budget													$ 1,000,000,000
Public utilities extension project schedule term													1 year
Percentage of approval required to change primary construction contractor													90.00%
Percentage of approval required for material amendments													67.00%
Estimated in-service capital cost																		$ 4,418,000,000
Additional construction capital costs									$ 3,300,000,000												$ 4,400,000,000
Construction In progress, before payments																4,800,000,000
Retail rate of return on common equity																								10.95%
Public utilities, approved return on equity										10.00%
Return on equity reduction, negative impact on earnings																25,000,000	20,000,000
Production tax credit amount per unit net present value																500,000,000
Scenario, Forecast | GEORGIA POWER CO
Loss Contingencies [Line Items]
Customer refund															$ 44,000,000
Scenario, Forecast | Plant Vogtle Units 3 And 4 | GEORGIA POWER CO
Loss Contingencies [Line Items]
Construction financing costs														$ 3,100,000,000
Customer refunds, number of installments | installment												3
Customer refunds, amount per customer												$ 25
Additional construction capital costs			$ 450,000,000
Amendment to estimated in-service capital cost																				$ 5,680,000,000
Public utilities, approved return on equity	5.30%	8.30%
Return on equity reduction, negative impact on earnings															$ 120,000,000				$ 585,000,000
FFB Loan | GEORGIA POWER CO
Loss Contingencies [Line Items]
Line of credit facility, maximum borrowing capacity								$ 2,600,000,000								$ 2,600,000,000	$ 2,600,000,000
Loan Guarantee Agreement | GEORGIA POWER CO
Loss Contingencies [Line Items]
Credit facility conditional borrowing commitment																						$ 1,670,000,000
Subsequent Event | Plant Vogtle Units 3 And 4 | GEORGIA POWER CO
Loss Contingencies [Line Items]
Increase (decrease) in tariff				$ 50,000,000
Customer refund				$ 188,000,000
Additional construction capital costs					$ 542,000,000
Vogtle Owners [Member] | Plant Vogtle Units 3 And 4 | GEORGIA POWER CO
Loss Contingencies [Line Items]
Period of notice required in the event letters of credit are not renewed							30 days