COMMITMENTS AND CONTINGENCIES (Details)	12 Months Ended
	Dec. 31, 2017 USD ($)	Dec. 31, 2016 USD ($)	Dec. 31, 2015 USD ($)
Commitments and contingencies
Operating Leases, Rent Expense	$ 10.0	$ 10.2	$ 11.1
Operating Leases, Future Minimum Payments Due, Next Twelve Months	34,000,000
Operating Leases, Future Minimum Payments, Due in Two Years	30,000,000
Operating Leases, Future Minimum Payments, Due in Three Years	6,000,000
Operating Leases, Future Minimum Payments, Due in Four Years	6,000,000
Operating Leases, Future Minimum Payments, Due in Five Years	5,000,000
Operating Leases, Future Minimum Payments, Due Thereafter	31,000,000
Guarantor Obligations, Maximum Exposure, Undiscounted	1,800,000,000
Asset Retirement Obligation Other Conditional Obligations	360,000,000
Asset Retirement Obligation	568,000,000	558,000,000	520,000,000
Asset Retirement Obligation, Liabilities Incurred	0	0
Asset Retirement Obligation, Liabilities Settled	(10,000,000)	(11,000,000)
Asset Retirement Obligation, Accretion Expense	25,000,000	23,000,000
Asset Retirement Obligation, Revision of Estimate	$ (5,000,000)	26,000,000
Environmental
Emission Rate Standard For Coal Fired Power Plants Under Clean Air Act	1,400
Emission Rate Standard for Natural Gas	1,000
Goal For Reduced Carbon Dioxide Emissions From 2005 Levels By 2030 Under Clean Air Act	32.00%
Number of States affected by CSAPR	28
SCE&G
Commitments and contingencies
Operating Leases, Rent Expense	$ 11.4	12.2	12.3
Operating Leases, Future Minimum Payments Due, Next Twelve Months	26,000,000
Operating Leases, Future Minimum Payments, Due in Two Years	23,000,000
Operating Leases, Future Minimum Payments, Due in Three Years	1,000,000
Operating Leases, Future Minimum Payments, Due in Four Years	1,000,000
Operating Leases, Future Minimum Payments, Due in Five Years	0
Operating Leases, Future Minimum Payments, Due Thereafter	17,000,000
Asset Retirement Obligation Other Conditional Obligations	321,000,000
Asset Retirement Obligation	529,000,000	522,000,000	$ 488,000,000
Asset Retirement Obligation, Liabilities Incurred	0	0
Asset Retirement Obligation, Liabilities Settled	(9,000,000)	(11,000,000)
Asset Retirement Obligation, Accretion Expense	23,000,000	22,000,000
Asset Retirement Obligation, Revision of Estimate	(7,000,000)	$ 23,000,000
Nuclear Insurance
scg_Maximum Insurance Coverage for each Nuclear Plant by ANI	450,000,000
Federal Limit on Public Liability Claims from Nuclear Incident Approximate	13,400,000,000
Maximum liability assessment per reactor for each nuclear incident	127,300,000
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
Maximum Insurance Coverage for Nuclear events	2,750,000,000
NEIL Maximum Insurance Coverage To Nuclear Facility For Property Damage And Outage Costs From Non-Nuclear Event	2,330,000,000
Maximum prosepective insurance premium per nuclear incident	22,300,000
Maximum amount of coverage to nuclear facility for property damage and outage costs	2,750,000,000
EMANI Maximum Insurance Coverage for Summer Station Unit 1 For Property Damage And Outage Costs From Non-Nuclear Event	415,000,000
EMANI Maximum Retrospective Premium Assessment	2,000,000
Environmental
Environmental Remediation Expense	9,900,000
Deferred costs, net of costs previously recovered through rates and insurance settlements included in regulatory assets	24,600,000
Nuclear Generation
Asset Retirement Obligation Nuclear Decommissioning	208,000,000
SCE&G | SCE&G
Nuclear Insurance
Maximum yearly assessment per reactor	$ 12,600,000