LONG-TERM AND SHORT-TERM DEBT (Details 2) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2018	Dec. 31, 2017
Debt Instrument [Line Items]
Letter of Credit issued	$ 43.4
Related Party Transaction, Due from (to) Related Party, Current	197.0	$ 28.0
Line of Credit Facility, Maximum Borrowing Capacity	2,000.0	2,000.0
Borrowings under LOC	$ 100.0
Weighted Average interest rate on LOC borrowing	2.97%
Commercial Paper	$ 248.0	350.3
Letters of Credit Outstanding, Amount	46.7	3.3
Line of Credit Facility, Remaining Borrowing Capacity	1,605.3	1,646.4
five year credit [Domain]
Debt Instrument [Line Items]
Line of Credit Facility, Maximum Borrowing Capacity	1,300.0	1,300.0
SCANA [Member]
Debt Instrument [Line Items]
Line of Credit Facility, Maximum Borrowing Capacity	400.0	400.0
Commercial Paper	$ 10.9	$ 0.0
Debt, Weighted Average Interest Rate	2.70%	0.00%
Letters of Credit Outstanding, Amount	$ 46.4	$ 3.0
Line of Credit Facility, Remaining Borrowing Capacity	342.7	397.0
SCEG including Fuel Company [Member]
Debt Instrument [Line Items]
Line of Credit Facility, Maximum Borrowing Capacity	1,400.0	1,400.0
Commercial Paper	$ 145.8	$ 251.6
Debt, Weighted Average Interest Rate	2.75%	1.92%
Letters of Credit Outstanding, Amount	$ 0.3	$ 0.3
Line of Credit Facility, Remaining Borrowing Capacity	1,153.9	1,148.1
Fuel Company [Member]
Debt Instrument [Line Items]
Line of Credit Facility, Maximum Borrowing Capacity	500.0	500.0
Long-Term Line of Credit - SC Fuel Co only	500.0	500.0
SCEG
Debt Instrument [Line Items]
Related Party Transaction, Due from (to) Related Party, Current	149.0	37.0
Line of Credit Facility, Maximum Borrowing Capacity	700.0	700.0
Long-term Line of Credit - SCE&G only	200.0	200.0
PSNC Energy [Member]
Debt Instrument [Line Items]
Line of Credit Facility, Maximum Borrowing Capacity	200.0	200.0
Commercial Paper	$ 91.3	$ 98.7
Debt, Weighted Average Interest Rate	2.52%	1.93%
Line of Credit Facility, Remaining Borrowing Capacity	$ 108.7	$ 101.3