COMMITMENTS AND CONTINGENCIES (Details) - USD ($)	9 Months Ended	12 Months Ended
	Sep. 30, 2015	Dec. 31, 2014	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2013
Commitments and contingencies
Asset Retirement Obligation	$ 489,000,000	$ 563,000,000				$ 576,000,000
Asset Retirement Obligation, Liabilities Incurred	0	3,000,000
Asset Retirement Obligation, Liabilities Settled	(15,000,000)	(6,000,000)
Asset Retirement Obligation, Accretion Expense	20,000,000	26,000,000
Asset Retirement Obligation, Revision of Estimate	$ (79,000,000)	(36,000,000)
Nuclear Generation
Emission Rate Standard For Coal Fired Power Plants Under Clean Air Act	1,400
Emission Rate Standard For Gas Fired Power Plants Under Clean Air Act	1,000
Goal For Reduced Carbon Dioxide Emissions From 2005 Levels By 2030 Under Clean Air Act	32.00%
NPDES permit renewal permit period	five
Forecasted Incremental Capital Costs Associated With Schedule Delays, 2015 Petition	$ 539,000,000
EPC Contract Amendment, New Nuclear Construction Completion Bonus	151,000,000
EPC Contract Amendment, Fixed Price Option, Increase In Total New Nuclear Project Cost	774,000,000
Regulatory Assets, Noncurrent	1,884,000,000	1,823,000,000
Asset Retirement Obligation Other Conditional Obligations	315,000,000	362,000,000
SCEG
Commitments and contingencies
Asset Retirement Obligation	460,000,000	536,000,000				$ 547,000,000
Asset Retirement Obligation, Liabilities Incurred	0	3,000,000
Asset Retirement Obligation, Liabilities Settled	(15,000,000)	(6,000,000)
Asset Retirement Obligation, Accretion Expense	18,000,000	25,000,000
Asset Retirement Obligation, Revision of Estimate	(79,000,000)	(33,000,000)
Nuclear Insurance
Federal Limit on Public Liability Claims from Nuclear Incident Approximate	12,900,000,000
Maximum Insurance Coverage for each Nuclear Plant by ANI	375,000,000
Maximum liability assessment per reactor for each nuclear incident	127,300,000
Maximum Federal Limit on Public Liability Claims Per Incident for Each Year	12,600,000
Maximum yearly assessment per reactor	18,900,000
Maximum Federal Limit on Public Liability Claims per Reactor for each Nuclear Incident at 2/3	$ 84,800,000
Inflation adjustment period for nuclear insurance	5
Maximum retrospective insurance premium per nuclear incident	$ 45,900,000
Maximum amount of coverage to nuclear facility for property damage and outage costs	2,750,000,000
Maximum amount of coverage for accidental property damage	500,000,000
Maximum loss for a single nuclear incident	$ 2,750,000,000
Environmental
Number of MGP decommissioned sites that contain residues of byproduct chemicals	4
Site Contingency MGP Estimated Environmental Remediation Costs	$ 19,000,000
Deferred costs net of costs previously recovered through rates and insurance settlements included in regulatory assets	$ 34,700,000
Nuclear Generation
Current ownership share in New Unit	55.00%
Total additional ownership in new units	5.00%
Additional ownership in new units	1.00%
Additional ownership in new units, dollars	$ 750,000,000
Emission Rate Standard For Coal Fired Power Plants Under Clean Air Act	1,400
Emission Rate Standard For Gas Fired Power Plants Under Clean Air Act	1,000
Goal For Reduced Carbon Dioxide Emissions From 2005 Levels By 2030 Under Clean Air Act	0.00%
EPC Contract Amendment, Settlement Of Outstanding New Nuclear Construction Disputes	$ 165,000,000
EPC Contract Amendment, Credit Applied To Target Component Of New Units Contract Price	27,000,000
EPC Contract Amendment, Cap On Delay Oriented Liquidated Damages Per New Nuclear Unit	255,000,000
EPC Contract Amendment, Revised Construction Milestone Payment Schedule, Per Month	55,000,000
EPC Contract Amendment, Increase In Total New Nuclear Project Cost	286,000,000
Total New Nuclear Project Cost Approved By SCPSC In September 2015	7,000,000,000
EPC Contract Amendment, Fixed Price Option, Project Cost Approved By SCPSC Including Fixed Option Price Increase	7,600,000,000.0
EPC Contract Amendment, Total New Nuclear Project Cost Approved By SCPSC Including Amendment Increase	7,000,000,000
EPC Contract Amendment, Fixed Price Option, Price For New Nuclear Construction After June 2015	3,345,000,000.000
EPC Contract Amendment, Fixed Price Option, Cap On Delay Oriented Liquidated Damages Per New Nuclear Unit	186,000,000
EPC Contract Amendment, Fixed Price Option, New Nuclear Construction Completion Bonus	83,000,000
Regulatory Assets, Noncurrent	1,808,000,000	1,745,000,000
Asset Retirement Obligation Nuclear Decommissioning	174,000,000	201,000,000
Asset Retirement Obligation Other Conditional Obligations	286,000,000	$ 335,000,000
Summer Station New Units [Domain]
Nuclear Insurance
Jointly Owned Utility Plant, Ownership Amount of Construction Work in Progress	3,300,000,000
jointly owned utility plant ownership, construction financing cost	$ 2,425,000,000
Nuclear Generation
Jointly Owned Utility Plant, Proportionate Ownership Share	55.00%
Jointly Owned Utility Plant, Additional Ownership Of New Units	5.00%
Nuclear Production Tax Credits	$ 1,400,000,000
Nuclear Production Tax Credit realization period	8
EPC Contract Amendment, Settlement Of Outstanding New Nuclear Construction Disputes	$ 300,000,000
EPC Contract Amendment, Credit Applied To Target Component Of New Units Contract Price	50,000,000
EPC Contract Amendment, Cap On Delay Oriented Liquidated Damages Per New Nuclear Unit	463,000,000
EPC Contract Amendment, New Nuclear Construction Completion Bonus	275,000,000
EPC Contract Amendment, Revised Construction Milestone Payment Schedule, Per Month	100,000,000
EPC Contract Amendment, Fixed Price Option, Price For New Nuclear Construction After June 2015	6,082,000,000.000
EPC Contract Amendment, Fixed Price Option, Cap On Delay Oriented Liquidated Damages Per New Nuclear Unit	338,000,000
EPC Contract Amendment, Fixed Price Option, New Nuclear Construction Completion Bonus	$ 150,000,000
Summer Station New Units [Domain] | SCEG
Nuclear Generation
Jointly Owned Utility Plant, Proportionate Ownership Share	55.00%
Nuclear Production Tax Credits	$ 1,400,000,000
Nuclear Production Tax Credit realization period	8
Capital costs, owners [Domain]
Nuclear Generation
Forecasted incremental capital costs, 2015 petition	$ 245,000,000
Forecasted Total Capital Costs, 2015 Petition	5,200,000,000.0
Capital costs, owners [Domain] | SCEG
Nuclear Generation
Forecasted incremental capital costs, 2015 petition	245,000,000
Capital costs, Other [Domain] [Domain]
Nuclear Generation
Forecasted incremental capital costs, 2015 petition	453,000,000
Forecasted Total Capital Costs, 2015 Petition	6,800,000,000.0
Capital costs, Other [Domain] [Domain] | SCEG
Nuclear Generation
Forecasted incremental capital costs, 2015 petition	$ 453,000,000
Scenario, Forecast [Member] | SCEG
Nuclear Generation
Additional ownership in new units			2.00%	2.00%	1.00%