Contingencies and Regulatory Matters - Textual - GPC - Contingencies and Regulatory Matters (Details)											1 Months Ended	3 Months Ended	12 Months Ended				84 Months Ended	90 Months Ended
	Jan. 01, 2021	Jan. 01, 2020	Feb. 28, 2018 USD ($)	Jan. 30, 2018 USD ($)	Jan. 11, 2018 USD ($)	Dec. 08, 2017 payment	Jun. 09, 2017	Dec. 20, 2016 USD ($)	Jan. 01, 2016 USD ($)	Jan. 01, 2013	Jul. 31, 2016 MW	Sep. 30, 2018 USD ($) installment	Dec. 31, 2018 USD ($)	Dec. 31, 2017 USD ($) MW	Dec. 31, 2015 USD ($)	Dec. 31, 2009 utility	Dec. 31, 2022	Jun. 30, 2016 USD ($)	Jun. 30, 2019 USD ($)	Dec. 31, 2016 USD ($)	Aug. 31, 2016	May 01, 2016 USD ($)	Dec. 31, 2013
Schedule of Regulatory Assets and Liabilities [Line Items]
Net regulatory assets														$ (1,894,000,000)						$ 5,866,000,000
GEORGIA POWER CO
Schedule of Regulatory Assets and Liabilities [Line Items]
Number of construction units approved | utility																2
Environmental exit costs, assets previously disposed, liability for remediation														$ 22,000,000						17,000,000
Claims awarded to companies related to nuclear fuel disposal litigation															$ 18,000,000
Increase (decrease) in base tariff rate									$ 49,000,000
Increase (decrease) in ECCR tariff									75,000,000
Increase (decrease) in demand side management tariff									3,000,000
Increase (decrease) in municipal franchise fee tariff									13,000,000
Increase (decrease) in revenue to be received from base rate change									$ 140,000,000
Retail rate of return on common equity										10.95%
Portion of actual earnings above approved ROE band retained by subsidiary company										33.33%
Portion of actual earnings above approved ROE band refunded to customers										66.67%
Capacity of units included in application request by subsidiaries for future period requests | MW											1,200
Capacity of renewable resources approved for self-build | MW											200
Approved capacity of units for solar generation resources | MW														510
Approved increase (decrease) in annual billing based on fuel cost recovery rate															$ (350,000,000)							$ (313,000,000)
Adjustment to fuel cost recovery rate if under recovered fuel balance exceeds budget thereafter														$ 200,000,000
Required period for options and hedges														48 months
Over recovered fuel balance														$ 165,000,000						84,000,000
Accrual under alternate rate plan														30,000,000
Net regulatory assets														$ 232,000,000						3,506,000,000
Scenario, Forecast | GEORGIA POWER CO
Schedule of Regulatory Assets and Liabilities [Line Items]
Customer refund													$ 44,000,000
Scenario, Forecast | Georgia Power And Atlanta Gas Light Company
Schedule of Regulatory Assets and Liabilities [Line Items]
Percentage basis net merger savings																	40.00%
Customers | Scenario, Forecast
Schedule of Regulatory Assets and Liabilities [Line Items]
Percentage basis net merger savings																	60.00%
Minimum | GEORGIA POWER CO
Schedule of Regulatory Assets and Liabilities [Line Items]
Retail rate of return on common equity										10.00%
Maximum | GEORGIA POWER CO
Schedule of Regulatory Assets and Liabilities [Line Items]
Retail rate of return on common equity										12.00%
Capacity of renewable resources considered for renewable commercial and industrial program | MW											200
Maximum | Scenario, Forecast | GEORGIA POWER CO
Schedule of Regulatory Assets and Liabilities [Line Items]
Cost recovery, new nuclear																			$ 99,000,000
Cost recovery, estimate, nuclear fuel																			$ 50,000,000
Plant Vogtle Units 3 And 4 | GEORGIA POWER CO
Schedule of Regulatory Assets and Liabilities [Line Items]
Number of payments made | payment						3
Additional construction capital costs								$ 3,300,000,000										$ 4,400,000,000
Retail rate of return on common equity																							10.95%
Percent ownership														45.70%
Cost settlement agreement revised forecast														$ 8,800,000,000
Project capital cost forecast														7,300,000,000
Public utilities, approved return on equity									10.00%
Plant Vogtle Units 3 And 4 | Scenario, Forecast | GEORGIA POWER CO
Schedule of Regulatory Assets and Liabilities [Line Items]
Additional construction capital costs			$ 450,000,000
Customer refunds, number of installments | installment												3
Public utilities, approved return on equity	5.30%	8.30%
Customer refunds, amount per customer												$ 25
Plant Mitchell Units 3, 4A, and 4B | GEORGIA POWER CO
Schedule of Regulatory Assets and Liabilities [Line Items]
Capacity of units included in request for decertification of units | MW											217
Plant Kraft Unit 1 | GEORGIA POWER CO
Schedule of Regulatory Assets and Liabilities [Line Items]
Capacity of units included in request for decertification of units | MW											17
Intercession City Combustion Turbine | GEORGIA POWER CO
Schedule of Regulatory Assets and Liabilities [Line Items]
Capacity of units included in request to sell | MW											143
Percent ownership																					33.00%
Storm damage reserves | GEORGIA POWER CO
Schedule of Regulatory Assets and Liabilities [Line Items]
Incremental restoration costs														260,000,000
Net regulatory assets														$ 333,000,000						$ 206,000,000
Vogtle Owners [Member] | Plant Vogtle Units 3 And 4 | GEORGIA POWER CO
Schedule of Regulatory Assets and Liabilities [Line Items]
Period of notice required in the event letters of credit are not renewed							30 days
Subsequent Event | Plant Vogtle Units 3 And 4 | GEORGIA POWER CO
Schedule of Regulatory Assets and Liabilities [Line Items]
Additional construction capital costs					$ 542,000,000
Increase (decrease) in tariff				$ 50,000,000
Customer refund				$ 188,000,000