LONG-TERM AND SHORT-TERM DEBT (Details 2) - USD ($) $ in Millions	3 Months Ended	9 Months Ended
	Sep. 30, 2018	Sep. 30, 2018	Dec. 31, 2017
Debt Instrument [Line Items]
Interest Income, Related Party	$ 1.0	$ 3.0
Interest Expense, Related Party	1.1	2.5
Proceeds from Issuance of First Mortgage Bond		$ 300.0
interest rate on first mortgage bonds issued		4.25%
Borrowings under credit agreement		$ 100.0
Related Party Transaction, Due from (to) Related Party, Current	195.0	195.0	$ 28.0
Line of Credit Facility, Maximum Borrowing Capacity	2,000.0	2,000.0	2,000.0
Borrowings under LOC		40.0
Long-term Line of Credit	1,800.0	$ 1,800.0
Weighted Average interest rate on LOC borrowing		0.00%
Commercial Paper	314.2	$ 314.2	350.3
Letters of Credit Outstanding, Amount	37.6	37.6	3.3
Line of Credit Facility, Remaining Borrowing Capacity	1,608.2	1,608.2	1,646.4
Commercial paper borrowing limit	600.0	600.0
Repayments of First Mortgage Bond		$ 250.0
interest rate first mortgage bonds redeemed		6.50%
First Mortgage Bond rate [Domain]
Debt Instrument [Line Items]
interest rate on first mortgage bonds issued		3.50%
five year credit [Domain]
Debt Instrument [Line Items]
Line of Credit Facility, Maximum Borrowing Capacity	1,300.0	$ 1,300.0	1,300.0
SCANA [Member]
Debt Instrument [Line Items]
Borrowings under credit agreement		40.0
Line of Credit Facility, Maximum Borrowing Capacity	400.0	$ 400.0	400.0
Weighted Average interest rate on LOC borrowing		3.78%
Commercial Paper	$ 3.7	$ 3.7	$ 0.0
Debt, Weighted Average Interest Rate	3.20%	3.20%	0.00%
Letters of Credit Outstanding, Amount	$ 37.3	$ 37.3	$ 3.0
Line of Credit Facility, Remaining Borrowing Capacity	319.0	319.0	397.0
SCEG including Fuel Company [Member]
Debt Instrument [Line Items]
Line of Credit Facility, Maximum Borrowing Capacity	1,400.0	1,400.0	1,400.0
Borrowings under LOC		0.0
Commercial Paper	$ 173.2	$ 173.2	$ 251.6
Debt, Weighted Average Interest Rate	3.21%	3.21%	1.92%
Letters of Credit Outstanding, Amount	$ 0.3	$ 0.3	$ 0.3
Line of Credit Facility, Remaining Borrowing Capacity	1,226.5	1,226.5	1,148.1
Commercial paper borrowing limit	1,600.0	1,600.0
Genco
Debt Instrument [Line Items]
Commercial paper borrowing limit	200.0	200.0
Fuel Company [Member]
Debt Instrument [Line Items]
Line of Credit Facility, Maximum Borrowing Capacity	500.0	500.0	500.0
Long-Term Line of Credit - SC Fuel Co only	500.0	500.0	500.0
SCEG
Debt Instrument [Line Items]
Proceeds from Issuance of First Mortgage Bond		400.0
Related Party Transaction, Due from (to) Related Party, Current	177.0	177.0	37.0
Line of Credit Facility, Maximum Borrowing Capacity	700.0	700.0	700.0
Long-term Line of Credit	1,200.0	1,200.0
Long-term Line of Credit - SCE&G only	200.0	200.0	200.0
Repayments of First Mortgage Bond		$ 300.0
interest rate first mortgage bonds redeemed		5.25%
PSNC Energy [Member]
Debt Instrument [Line Items]
Line of Credit Facility, Maximum Borrowing Capacity	200.0	$ 200.0	200.0
Commercial Paper	$ 137.3	$ 137.3	$ 98.7
Debt, Weighted Average Interest Rate	3.13%	3.13%	1.93%
Line of Credit Facility, Remaining Borrowing Capacity	$ 62.7	$ 62.7	$ 101.3