v3.10.0.1
Regulatory Matters - Schedule of GPC Regulatory Assets and Liabilities (Details) - USD ($)
$ in Millions
 12 Months Ended
Dec. 31, 2019
Dec. 31, 2018
Dec. 31, 2017
Schedule of Regulatory Assets and Liabilities [Line Items]      
Total regulatory assets (liabilities), net   $ 720 $ (1,894)
Maximum      
Schedule of Regulatory Assets and Liabilities [Line Items]      
Life of new issue   50 years  
Deferred income tax credits      
Schedule of Regulatory Assets and Liabilities [Line Items]      
Total regulatory assets (liabilities), net   $ (6,455) (7,261)
Customer refunds      
Schedule of Regulatory Assets and Liabilities [Line Items]      
Total regulatory assets (liabilities), net   (293) (188)
Other regulatory liabilities      
Schedule of Regulatory Assets and Liabilities [Line Items]      
Total regulatory assets (liabilities), net   (132) (104)
Retiree benefit plans      
Schedule of Regulatory Assets and Liabilities [Line Items]      
Total regulatory assets (liabilities), net   $ 3,658 3,931
Retiree benefit plans | Maximum      
Schedule of Regulatory Assets and Liabilities [Line Items]      
Regulatory amortization period   15 years  
Asset retirement obligations-asset      
Schedule of Regulatory Assets and Liabilities [Line Items]      
Total regulatory assets (liabilities), net   $ 2,933 1,133
Deferred income tax charges      
Schedule of Regulatory Assets and Liabilities [Line Items]      
Total regulatory assets (liabilities), net   $ 799 814
Deferred income tax charges | Maximum      
Schedule of Regulatory Assets and Liabilities [Line Items]      
Regulatory amortization period   80 years  
Remaining net book value of retired assets      
Schedule of Regulatory Assets and Liabilities [Line Items]      
Total regulatory assets (liabilities), net   $ 211 306
Remaining net book value of retired assets | Maximum      
Schedule of Regulatory Assets and Liabilities [Line Items]      
Regulatory amortization period   8 years  
Loss on reacquired debt      
Schedule of Regulatory Assets and Liabilities [Line Items]      
Total regulatory assets (liabilities), net   $ 346 223
Vacation pay      
Schedule of Regulatory Assets and Liabilities [Line Items]      
Total regulatory assets (liabilities), net   $ 182 183
Regulatory amortization period   1 year  
Other regulatory assets      
Schedule of Regulatory Assets and Liabilities [Line Items]      
Total regulatory assets (liabilities), net   $ 581 625
Other regulatory assets | Maximum      
Schedule of Regulatory Assets and Liabilities [Line Items]      
Regulatory amortization period   50 years  
Georgia Power      
Schedule of Regulatory Assets and Liabilities [Line Items]      
Total regulatory assets (liabilities), net   $ 2,378 232
Costs recovered annually   2  
Customer refund liability, current   55  
Customer refund   $ 40  
Georgia Power | Scenario, Forecast      
Schedule of Regulatory Assets and Liabilities [Line Items]      
Customer refund $ 100    
Georgia Power | Maximum      
Schedule of Regulatory Assets and Liabilities [Line Items]      
Life of new issue   34 years  
Georgia Power | Maximum | Scenario, Forecast      
Schedule of Regulatory Assets and Liabilities [Line Items]      
Cost recovery, estimate, nuclear fuel 50    
Georgia Power | Deferred income tax credits      
Schedule of Regulatory Assets and Liabilities [Line Items]      
Total regulatory assets (liabilities), net   $ (3,080) (3,248)
Georgia Power | Customer refunds      
Schedule of Regulatory Assets and Liabilities [Line Items]      
Total regulatory assets (liabilities), net   (165) (188)
Georgia Power | Other regulatory liabilities      
Schedule of Regulatory Assets and Liabilities [Line Items]      
Total regulatory assets (liabilities), net   (7) (3)
Amortization of regulatory assets()   3  
Costs associated with construction to be completed   30  
Georgia Power | Retiree benefit plans      
Schedule of Regulatory Assets and Liabilities [Line Items]      
Total regulatory assets (liabilities), net   $ 1,295 1,313
Georgia Power | Retiree benefit plans | Maximum      
Schedule of Regulatory Assets and Liabilities [Line Items]      
Regulatory amortization period   14 years  
Georgia Power | Asset retirement obligations-asset      
Schedule of Regulatory Assets and Liabilities [Line Items]      
Total regulatory assets (liabilities), net   $ 2,644 945
ARO annual recovery   60  
Georgia Power | Deferred income tax charges      
Schedule of Regulatory Assets and Liabilities [Line Items]      
Total regulatory assets (liabilities), net   522 521
Deferred tax assets related to CWIP   145  
Deferred tax liabilities   610  
Georgia Power | Storm damage reserves      
Schedule of Regulatory Assets and Liabilities [Line Items]      
Total regulatory assets (liabilities), net   416 333
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 | Remaining net book value of retired assets | Scenario, Forecast      
Schedule of Regulatory Assets and Liabilities [Line Items]      
Amortization of regulatory assets() $ 4    
Georgia Power | Remaining net book value of retired assets | Maximum      
Schedule of Regulatory Assets and Liabilities [Line Items]      
Regulatory amortization period   3 years  
Georgia Power | Loss on reacquired debt      
Schedule of Regulatory Assets and Liabilities [Line Items]      
Total regulatory assets (liabilities), net   $ 277 127
Georgia Power | Vacation pay      
Schedule of Regulatory Assets and Liabilities [Line Items]      
Total regulatory assets (liabilities), net   $ 91 91
Regulatory amortization period   1 year  
Georgia Power | Other cost of removal obligations      
Schedule of Regulatory Assets and Liabilities [Line Items]      
Total regulatory assets (liabilities), net   $ 68 40
Georgia Power | Environmental remediation      
Schedule of Regulatory Assets and Liabilities [Line Items]      
Total regulatory assets (liabilities), net   55 49
Georgia Power | Other regulatory assets      
Schedule of Regulatory Assets and Liabilities [Line Items]      
Total regulatory assets (liabilities), net   $ 135 $ 106
Regulatory amortization period   24 months  
Georgia Power | Deferred Income Tax Charge, AROs, Cost Of Removal Obligations, Deferred Income Tax Credits | Maximum      
Schedule of Regulatory Assets and Liabilities [Line Items]      
Regulatory amortization period   65 years  
Georgia Power | Retiree Medicare Drug Subsidy      
Schedule of Regulatory Assets and Liabilities [Line Items]      
Total regulatory assets (liabilities), net   $ 17  
Georgia Power | Obsolete Inventories of Retired Units      
Schedule of Regulatory Assets and Liabilities [Line Items]      
Total regulatory assets (liabilities), net   31  
Plant Branch Units 1 Through 4 | Georgia Power      
Schedule of Regulatory Assets and Liabilities [Line Items]      
Net book value of planned units retirements   87  
Plant Mitchell Unit 3 | Georgia Power      
Schedule of Regulatory Assets and Liabilities [Line Items]      
Net book value of planned units retirements   $ 9