SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013	Sep. 30, 2012	Dec. 31, 2012	Dec. 31, 2013 SCEG MW	Sep. 30, 2013 SCEG MW	Mar. 31, 2013 SCEG	Dec. 31, 2012 SCEG MW	Sep. 30, 2013 Genco MW
Significant Accounting Policies
Number of coal fired units to be retired							2	6	6
Power Generation Capacity Megawatts										605
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%		47.00%		44.00%
Natural gas inventory, carrying amount	$ 23.2		$ 23.2		$ 19.6
Property, Plant and Equipment, Net	$ 315		$ 315		$ 306		$ 68		$ 57	$ 478
Power generation capacity six coal fired units							730
Power Capacity of Retired Unit									90
Power Capacity of unit to be retired						295
Earnings Per Share
Weighted Average Shares Outstanding - Basic	140.1	131.4	138.0	130.8
Incremental Common Shares Attributable to Share-based Payment Arrangements and Equity Forward Agreements	0	2.4	0.6	2.3
Weighted Average Number of Shares Outstanding, Diluted	140.1	133.8	138.6	133.1