DERIVATIVE FINANCIAL INSTRUMENTS Derivative Financial Instruments Offsetting Assets and Liabilities (Details) - USD ($) $ in Millions	Mar. 31, 2017	Dec. 31, 2016
Derivative [Line Items]
Derivative Asset, Fair Value, Gross Asset	$ 86	$ 90
Derivative Asset, Fair Value, Gross Liability	(1)	(4)
Derivative Asset	85	86
Derivative Liability, Fair Value, Gross Liability	57	67
Derivative Liability, Fair Value, Gross Asset	(1)	(3)
Derivative, Collateral, Right to Reclaim Securities	(8)	(9)
Derivative, Collateral, Right to Reclaim Cash	(30)	(29)
Derivative Liability, Fair Value, Amount Offset Against Collateral	18	26
Derivative Liability	56	64
Derivative, Collateral, Obligation to Return Securities	(8)	(9)
Derivative, Collateral, Obligation to Return Cash	0	0
Derivative Asset, Fair Value, Amount Offset Against Collateral	77	77
Derivative Financial Instruments, Liabilities [Member]
Derivative [Line Items]
Derivative Liability	27	35
Other Deferred Debits and Other Assets [Member]
Derivative [Line Items]
Derivative Asset	79	72
Prepayments [Member]
Derivative [Line Items]
Derivative Asset	4	9
Other Current Assets [Member]
Derivative [Line Items]
Derivative Asset	2	5
Other Deferred Credits and Other Liabilities [Member]
Derivative [Line Items]
Derivative Liability	29	29
Interest Rate Contract [Member]
Derivative [Line Items]
Derivative Asset, Fair Value, Gross Asset	77	71
Derivative Asset	77	71
Derivative Liability, Fair Value, Gross Liability	52	58
Derivative, Collateral, Right to Reclaim Securities	(8)	(9)
Derivative, Collateral, Right to Reclaim Cash	(29)	(29)
Derivative Liability, Fair Value, Amount Offset Against Collateral	15	20
Derivative Liability	52	58
Derivative, Collateral, Obligation to Return Securities	(8)	(9)
Derivative Asset, Fair Value, Amount Offset Against Collateral	69	62
Commodity Contract [Member]
Derivative [Line Items]
Derivative Asset, Fair Value, Gross Asset	4	9
Derivative Asset	4	9
Derivative Liability, Fair Value, Gross Liability		0
Derivative Liability, Fair Value, Amount Offset Against Collateral		0
Derivative Liability		0
Derivative Asset, Fair Value, Amount Offset Against Collateral	4	9
Other Energy Management Contract [Member]
Derivative [Line Items]
Derivative Asset, Fair Value, Gross Asset	5	10
Derivative Asset, Fair Value, Gross Liability	(1)	(4)
Derivative Asset	4	6
Derivative Liability, Fair Value, Gross Liability	5	9
Derivative Liability, Fair Value, Gross Asset	(1)	(3)
Derivative, Collateral, Right to Reclaim Cash	(1)
Derivative Liability, Fair Value, Amount Offset Against Collateral	3	6
Derivative Liability	4	6
Derivative Asset, Fair Value, Amount Offset Against Collateral	4	6
SCEG
Derivative [Line Items]
Derivative Asset	77	71
Derivative Liability	34	39
SCEG | Derivative Financial Instruments, Liabilities [Member]
Derivative [Line Items]
Derivative Liability	23	28
SCEG | Other Deferred Debits and Other Assets [Member]
Derivative [Line Items]
Derivative Asset	77	71
SCEG | Other Deferred Credits and Other Liabilities [Member]
Derivative [Line Items]
Derivative Liability	11	11
SCEG | Interest Rate Contract [Member]
Derivative [Line Items]
Derivative Asset, Fair Value, Gross Asset	77	71
Derivative Asset	77	71
Derivative Liability, Fair Value, Gross Liability	34	39
Derivative, Collateral, Right to Reclaim Securities	(8)	(9)
Derivative, Collateral, Right to Reclaim Cash	(9)	(9)
Derivative Liability, Fair Value, Amount Offset Against Collateral	17	21
Derivative Liability	34	39
Derivative, Collateral, Obligation to Return Securities	(8)	(9)
Derivative Asset, Fair Value, Amount Offset Against Collateral	$ 69	$ 62