FAIR VALUE MEASUREMENTS, INCLUDING DERIVATIVES (Details 2) (USD $) In Millions, unless otherwise specified	Mar. 31, 2013	Dec. 31, 2012
Carrying Amount
Financial instruments for which the carrying amount may not equal estimated fair value
Long-term debt	$ 5,211.7	$ 5,121.0
Estimated Fair Value
Financial instruments for which the carrying amount may not equal estimated fair value
Long-term debt	6,118.8	6,115.0
SCEG | Carrying Amount
Financial instruments for which the carrying amount may not equal estimated fair value
Long-term debt	3,811.0	3,722.0
SCEG | Estimated Fair Value
Financial instruments for which the carrying amount may not equal estimated fair value
Long-term debt	$ 4,534.8	$ 4,543.1