REGULATORY MATTERS - Schedule of GPC Regulatory Assets and Liabilities (Details) - USD ($) $ in Millions		12 Months Ended
	Jan. 01, 2020	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Schedule of Regulatory Assets and Liabilities [Line Items]
Total regulatory assets (liabilities), net		$ 3,838	$ 720
Maximum
Schedule of Regulatory Assets and Liabilities [Line Items]
Life of new issue		34 years
Deferred income tax credits
Schedule of Regulatory Assets and Liabilities [Line Items]
Total regulatory assets (liabilities), net		$ (6,301)	(6,455)
Deferred tax liabilities		778
Customer refunds
Schedule of Regulatory Assets and Liabilities [Line Items]
Total regulatory assets (liabilities), net		(285)	(293)
Other regulatory liabilities
Schedule of Regulatory Assets and Liabilities [Line Items]
Total regulatory assets (liabilities), net		(86)	(132)
Retiree benefit plans
Schedule of Regulatory Assets and Liabilities [Line Items]
Total regulatory assets (liabilities), net		$ 4,423	3,658
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		$ 4,381	2,933
Deferred income tax charges
Schedule of Regulatory Assets and Liabilities [Line Items]
Total regulatory assets (liabilities), net		$ 803	799
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		$ 1,275	211
Remaining net book value of retired assets | Maximum
Schedule of Regulatory Assets and Liabilities [Line Items]
Regulatory amortization period		18 years
Loss on reacquired debt
Schedule of Regulatory Assets and Liabilities [Line Items]
Total regulatory assets (liabilities), net		$ 323	346
Vacation pay
Schedule of Regulatory Assets and Liabilities [Line Items]
Total regulatory assets (liabilities), net		$ 186	182
Regulatory amortization period		1 year
Other regulatory assets
Schedule of Regulatory Assets and Liabilities [Line Items]
Total regulatory assets (liabilities), net		$ 492	581
Other regulatory assets | Maximum
Schedule of Regulatory Assets and Liabilities [Line Items]
Regulatory amortization period		8 years
Georgia Power
Schedule of Regulatory Assets and Liabilities [Line Items]
Total regulatory assets (liabilities), net		$ 3,507	2,378
Costs recovered annually		2	2	$ 2
Portion of actual earnings above approved ROE band refunded to customers, value		60
Customer refund liability, current		$ 105
Georgia Power | Maximum
Schedule of Regulatory Assets and Liabilities [Line Items]
Life of new issue		33 years
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		(3,078)	(3,080)
Georgia Power | Customer refunds
Schedule of Regulatory Assets and Liabilities [Line Items]
Total regulatory assets (liabilities), net		(229)	(165)
Portion of actual earnings above approved ROE band refunded to customers, value		110	100
Customer refund liability, current		105	55
Georgia Power | Other regulatory liabilities
Schedule of Regulatory Assets and Liabilities [Line Items]
Total regulatory assets (liabilities), net		(16)	(7)
Amortization of regulatory assets		10
Costs associated with construction to be completed		22
Georgia Power | Retiree benefit plans
Schedule of Regulatory Assets and Liabilities [Line Items]
Total regulatory assets (liabilities), net		$ 1,516	1,295
Georgia Power | Retiree benefit plans | Maximum
Schedule of Regulatory Assets and Liabilities [Line Items]
Regulatory amortization period		13 years
Georgia Power | Asset retirement obligations-asset
Schedule of Regulatory Assets and Liabilities [Line Items]
Total regulatory assets (liabilities), net		$ 3,119	2,644
ARO annual recovery		5
Georgia Power | Deferred income tax charges
Schedule of Regulatory Assets and Liabilities [Line Items]
Total regulatory assets (liabilities), net		523	522
Deferred tax assets related to CWIP		145
Deferred tax liabilities		660
Georgia Power | Storm damage reserves
Schedule of Regulatory Assets and Liabilities [Line Items]
Total regulatory assets (liabilities), net		410	416
Georgia Power | Remaining net book value of retired assets
Schedule of Regulatory Assets and Liabilities [Line Items]
Total regulatory assets (liabilities), net		$ 596	127
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		$ 262	277
Georgia Power | Vacation pay
Schedule of Regulatory Assets and Liabilities [Line Items]
Total regulatory assets (liabilities), net		$ 93	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		$ 156	68
Georgia Power | Environmental remediation
Schedule of Regulatory Assets and Liabilities [Line Items]
Total regulatory assets (liabilities), net		52	55
Georgia Power | Fuel-hedging (realized and unrealized) losses
Schedule of Regulatory Assets and Liabilities [Line Items]
Total regulatory assets (liabilities), net		$ 53	15
Regulatory amortization period		4 years
Georgia Power | Other regulatory assets
Schedule of Regulatory Assets and Liabilities [Line Items]
Total regulatory assets (liabilities), net		$ 50	120
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		60 years
Georgia Power | Retiree Medicare Drug Subsidy
Schedule of Regulatory Assets and Liabilities [Line Items]
Total regulatory assets (liabilities), net		$ 13
Georgia Power | Obsolete Inventories of Retired Units
Schedule of Regulatory Assets and Liabilities [Line Items]
Total regulatory assets (liabilities), net			31
Plant Hammond Units 1 through 4 | Georgia Power
Schedule of Regulatory Assets and Liabilities [Line Items]
Net book value of planned units retirements		488
Plant Branch Units 1 Through 4 | Georgia Power
Schedule of Regulatory Assets and Liabilities [Line Items]
Net book value of planned units retirements		69	87
Plant McIntosh Unit 1 | Georgia Power
Schedule of Regulatory Assets and Liabilities [Line Items]
Net book value of planned units retirements		30
Plant Mitchell Unit 3 | Georgia Power
Schedule of Regulatory Assets and Liabilities [Line Items]
Net book value of planned units retirements		$ 8	$ 9
Subsequent Event | Major storms | Georgia Power
Schedule of Regulatory Assets and Liabilities [Line Items]
Recoveries for storm damage	$ 213