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