AFFILIATED TRANSACTIONS - SCEG AFFILIATED TRANSACTIONS -SCEG (Details) (USD $) In Millions, unless otherwise specified				9 Months Ended	12 Months Ended		9 Months Ended
	Sep. 30, 2012	Dec. 31, 2011	Sep. 30, 2012 Canadys Refined Coal LLC [Member]	Sep. 30, 2012 Cope Refined Coal LLC [Member]	Dec. 31, 2011 Cope Refined Coal LLC [Member]	Sep. 30, 2011 Cope Refined Coal LLC [Member]	Sep. 30, 2012 CGT [Member]	Sep. 30, 2011 CGT [Member]	Sep. 30, 2012 Retail Gas Marketing and Energy Marketing	Sep. 30, 2011 Retail Gas Marketing and Energy Marketing	Dec. 31, 2011 Retail Gas Marketing and Energy Marketing
Related Party Transaction [Line Items]
Related Party Transaction Purchases from Related Party				$ 87.3	$ 100.9		$ 27.1	$ 22.8
Due to Affiliate, Current							2.8	2.5	10.1		13.2
Equity Method Investment, Ownership Percentage			40.00%	10.00%
Increase (Decrease) Due from Affiliates				10.8	8.5
Cost of Natural Gas Purchases									84.0	146.6
Equity Method Investment, Dividends or Distributions				10.8	8.6
Energy Related Inventory, Coal				86.9		100.5
Related Party Transaction, Due from (to) Related Party, Current	49.3	58.5
Accounts Payable, Related Parties, Current	$ 45	$ 43