SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES (Details) $ in Millions	6 Months Ended
	Jun. 30, 2015 USD ($) MW	Dec. 31, 2014 USD ($)	Dec. 31, 2013	Dec. 31, 2012
Asset Management and Supply Service Agreements
Property, Plant and Equipment, Net	$ 284.0	$ 284.0
SCEG
Significant Accounting Policies
Number of coal fired units to be retired	3			6
Number of Units retired	3		3
Asset Management and Supply Service Agreements
Property, Plant and Equipment, Net	$ 67.0	$ 67.0
Genco
Significant Accounting Policies
Power Generation Capacity Megawatts | MW	605
Asset Management and Supply Service Agreements
Property, Plant and Equipment, Net	$ 494.0
PSNC Energy [Member]
Asset Management and Supply Service Agreements
Percentage of natural gas inventory held by counterparties under asset management and supply service agreements (as a percent)	47.00%	48.00%
Natural gas inventory, carrying amount	$ 13.8	$ 26.1
PercentOfStorageFeesCreditedToRatePayers	75.00%