Regulatory Matters - GPC Regulatory Matters (Details) $ in Millions				1 Months Ended			12 Months Ended				84 Months Ended
	Jan. 31, 2019 MW	Apr. 03, 2018 USD ($)	Jan. 01, 2013	Feb. 29, 2020 USD ($)	Jun. 30, 2019 USD ($)	Oct. 31, 2018 USD ($)	Dec. 31, 2019 USD ($)	Dec. 31, 2018 USD ($) capacity_based_request MW	Dec. 31, 2017 USD ($)	Dec. 31, 2016 USD ($)	Dec. 31, 2022	May 01, 2016 USD ($)
Schedule of Regulatory Assets and Liabilities [Line Items]
Effective income tax rate								16.30%	13.30%	27.30%
Deferred income taxes								$ 94	$ 166	$ (127)
Total regulatory assets (liabilities), net								720	(1,894)
Other regulatory assets, current								525	604
Other regulatory assets								8,308	6,943
Remaining net book value of retired assets
Schedule of Regulatory Assets and Liabilities [Line Items]
Total regulatory assets (liabilities), net								$ 211	$ 306
Maximum | Remaining net book value of retired assets
Schedule of Regulatory Assets and Liabilities [Line Items]
Regulatory amortization period								8 years
Scenario, Forecast | Customers
Schedule of Regulatory Assets and Liabilities [Line Items]
Percentage basis net merger savings											60.00%
Georgia Power And Atlanta Gas Light Company | Scenario, Forecast
Schedule of Regulatory Assets and Liabilities [Line Items]
Percentage basis net merger savings											40.00%
Georgia Power
Schedule of Regulatory Assets and Liabilities [Line Items]
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%
Customer refund liability, noncurrent								$ 330
Customer refund								40
Customer refund liability in absence of base rate case		$ 185						$ 4
Contract with customer, liability, bill credits						$ 130
Effective income tax rate								21.30%	36.70%	36.70%
Deferred income taxes		$ (700)						$ (260)	$ 458	$ 383
Retail regulatory equity ratio								0.55
Approved capacity of units for solar generation resources (mw) | MW								1,000
Proposed capacity of units for investment portfolio (mw) | MW								50
Proposed capacity of units for certification (in mw) | MW								25
Number of capacity-based requests | capacity_based_request								2
Approved increase (decrease) in annual billing based on fuel cost recovery rate												$ 313
Adjustment to fuel cost recovery rate if under recovered fuel balance exceeds budget thereafter								$ 200
Over recovered fuel balance								$ 115	165
Required period for options and hedges								48 months
Total regulatory assets (liabilities), net								$ 2,378	232
Other regulatory assets, current								199	205
Other regulatory assets								4,902	2,932
Georgia Power | Remaining net book value of retired assets
Schedule of Regulatory Assets and Liabilities [Line Items]
Total regulatory assets (liabilities), net								127	146
Georgia Power | Storm damage reserves
Schedule of Regulatory Assets and Liabilities [Line Items]
Total regulatory assets (liabilities), net								416	333
Georgia Power | Property damage reserves-liability
Schedule of Regulatory Assets and Liabilities [Line Items]
Other regulatory assets, current								30
Other regulatory assets								$ 386	$ 303
Georgia Power | Minimum
Schedule of Regulatory Assets and Liabilities [Line Items]
Retail rate of return on common equity			10.00%
Georgia Power | Maximum
Schedule of Regulatory Assets and Liabilities [Line Items]
Retail rate of return on common equity			12.00%
Retail regulatory equity ratio		0.55
Georgia Power | Maximum | Remaining net book value of retired assets
Schedule of Regulatory Assets and Liabilities [Line Items]
Regulatory amortization period								3 years
Georgia Power | Scenario, Forecast
Schedule of Regulatory Assets and Liabilities [Line Items]
Customer refund							$ 100
Contract with customer, liability, bill credits				$ 105	$ 95
Georgia Power | Scenario, Forecast | Maximum
Schedule of Regulatory Assets and Liabilities [Line Items]
Cost recovery, new nuclear					$ 99
Cost recovery, estimate, nuclear fuel							$ 50
Georgia Power | Deferred income tax charges
Schedule of Regulatory Assets and Liabilities [Line Items]
Regulatory liabilities								$ 610
Georgia Power | State and Local Jurisdiction
Schedule of Regulatory Assets and Liabilities [Line Items]
Effective income tax rate		6.00%
Georgia Power | State and Local Jurisdiction | Scenario, Forecast
Schedule of Regulatory Assets and Liabilities [Line Items]
Effective income tax rate							5.75%
Hurricane Michael | Georgia Power | Storm damage reserves
Schedule of Regulatory Assets and Liabilities [Line Items]
Incremental restoration costs								115
Hurricanes Irma and Matthew | Georgia Power | Storm damage reserves
Schedule of Regulatory Assets and Liabilities [Line Items]
Incremental restoration costs								250
Plant Hammond Units 1 through 4 | Georgia Power
Schedule of Regulatory Assets and Liabilities [Line Items]
Net book value of planned units retirements								520
Plant McIntosh Unit 1 | Georgia Power
Schedule of Regulatory Assets and Liabilities [Line Items]
Net book value of planned units retirements								$ 40
Subsequent Event | Plant Hammond Units 1 through 4 | Georgia Power
Schedule of Regulatory Assets and Liabilities [Line Items]
Capacity of units included in request for decertification of units (mw) | MW	840
Subsequent Event | Plant McIntosh Unit 1 | Georgia Power
Schedule of Regulatory Assets and Liabilities [Line Items]
Capacity of units included in request for decertification of units (mw) | MW	142.5