COMMON EQUITY (Details) - USD ($) shares in Millions, $ in Millions	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017	Dec. 31, 2017
Schedule of Capitalization, Equity [Line Items]
Dividend Payment Restrictions Schedule, Description	0.6125
Common Stock, Shares Authorized	200.0
Common Stock, Shares, Outstanding	143.0		143.0
SCEG
Schedule of Capitalization, Equity [Line Items]
Retained Earnings, Appropriated	$ 95.3		$ 80.6
Common Stock, Shares Authorized	50.0
Common Stock, Shares, Outstanding	40.3		40.3
Preferred Stock, Shares Authorized	20.0
Preferred Stock, Shares Outstanding	0.0
PSNC Energy [Member]
Schedule of Capitalization, Equity [Line Items]
Dividend Payment Restrictions Schedule, Description	$30 million plus 85%
Cash distributions in allowed in excess	$ 100.0
Commodity Contract
Schedule of Capitalization, Equity [Line Items]
Derivative Instruments, Gain (Loss) Reclassified from Accumulated OCI into Income, Effective Portion, Net	(2.0)	$ 2.0
Interest Rate Contract [Member]
Schedule of Capitalization, Equity [Line Items]
Derivative Instruments, Gain (Loss) Reclassified from Accumulated OCI into Income, Effective Portion, Net	(2.0)	(2.0)
Gas Purchased for Resale [Member] [Member] | Cash Flow Hedging [Member] | Commodity Contract
Schedule of Capitalization, Equity [Line Items]
Derivative Instruments, Gain (Loss) Reclassified from Accumulated OCI into Income, Effective Portion, Net	2.0	(2.0)
Interest Expense [Member] | Cash Flow Hedging [Member] | Interest Rate Contract [Member]
Schedule of Capitalization, Equity [Line Items]
Derivative Instruments, Gain (Loss) Reclassified from Accumulated OCI into Income, Effective Portion, Net	$ 2.0	$ 2.0