SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES (Details) $ in Millions	6 Months Ended	12 Months Ended
	Jun. 30, 2016 USD ($) MW	Dec. 31, 2015 USD ($)
Significant Accounting Policies
Pre-tax gain on sale of CGT and SCI		$ 342.0
Property, Plant and Equipment, Net	$ 278.0	280.0
Reclassifications, Cash Flow Statement, Regulatory Assets, Use Of Cash	149.0
Reclassifications, Cash Flow Statement, Regulatory liabilities, Source of Cash	31.0
Reclassifications, Cash Flow Statement, Other assets, use of cash	(41.0)
Reclassifications, Cash Flow Statement, Derivative Financial Instruments, Source Of Cash	(133.0)
Reclassifications, Cash Flow Statement, Other Liabilities, Source Of Cash	(6.0)
SCEG
Significant Accounting Policies
Property, Plant and Equipment, Net	68.0	$ 68.0
Reclassifications, Cash Flow Statement, Regulatory Assets, Use Of Cash	149.0
Reclassifications, Cash Flow Statement, Regulatory liabilities, Source of Cash	31.0
Reclassifications, Cash Flow Statement, Other assets, use of cash	(41.0)
Reclassifications, Cash Flow Statement, Derivative Financial Instruments, Source Of Cash	(133.0)
Reclassifications, Cash Flow Statement, Other Liabilities, Source Of Cash	$ (6.0)
Genco
Significant Accounting Policies
Power Generation Capacity Megawatts | MW	605
Property, Plant and Equipment, Net	$ 485.0
PSNC Energy [Member]
Significant Accounting Policies
Percentage of natural gas inventory held by counterparties under asset management and supply service agreements (as a percent)	42.00%	46.00%
Natural gas inventory, carrying amount	$ 9.2	$ 17.7
PercentOfStorageFeesCreditedToRatePayers	75.00%