SEGMENT OF BUSINESS INFORMATION (Details) - USD ($) $ in Millions	3 Months Ended						9 Months Ended
	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Sep. 30, 2018	Sep. 30, 2017	Dec. 31, 2017
Segment Reporting Information [Line Items]
Electric Regulated Revenue	$ 669			$ 786			$ 1,767	$ 2,042
Revenues	0			0			0	0
Net Income (Loss) Available to Common Stockholders, Basic	67	$ 8	$ 169	34	$ 121	$ 171	244	326
Operating Income	183			122			475	693
Regulated Operating Revenue, Gas	122			123			631	584
Regulated and Unregulated Operating Revenue	926			1,076			2,948	3,249
Segment Assets	18,816						18,816		$ 18,739
Electric Operations
Segment Reporting Information [Line Items]
Electric Regulated Revenue				786				2,042
Revenues	0			1			3	4
Operating Income	217			127			396	555
Segment Assets	12,046						12,046		11,979
Gas Distribution
Segment Reporting Information [Line Items]
Revenues	0			0			1	1
Operating Income	(10)			(7)			107	110
Regulated and Unregulated Operating Revenue	122			123			631	584
Segment Assets	3,384						3,384		3,259
Gas Marketing [Member]
Segment Reporting Information [Line Items]
Revenues	35			35			95	93
Net Income (Loss) Available to Common Stockholders, Basic	1			1			21	17
Regulated and Unregulated Operating Revenue	135			167			550	623
Segment Assets	204						204		230
All Other [member]
Segment Reporting Information [Line Items]
Revenues	124			90			347	286
Net Income (Loss) Available to Common Stockholders, Basic	(30)			(7)			(79)	(14)
Operating Income	0			0			0	0
Regulated and Unregulated Operating Revenue	0			0			0	0
Segment Assets	1,071						1,071		1,042
Adjustments/Eliminations
Segment Reporting Information [Line Items]
Revenues	(159)			(126)			(446)	(384)
Net Income (Loss) Available to Common Stockholders, Basic	96			40			302	323
Operating Income	(24)			2			(28)	28
Regulated and Unregulated Operating Revenue	0			0			0	0
Segment Assets	2,111						2,111		2,229
SCEG
Segment Reporting Information [Line Items]
Electric Regulated Revenue	669			786			1,767	2,042
Operating Income	212			124			440	597
Regulated Operating Revenue, Gas	69			69			303	284
Net Income (Loss) Attributable to Parent	98			39			248	270
Regulated Operating Revenue	739			856			2,074	2,331
Segment Assets	16,129						16,129		15,946
SCEG | Electric Operations
Segment Reporting Information [Line Items]
Electric Regulated Revenue				787				2,046
Operating Income	216			126			396	555
Regulated Operating Revenue	670						1,770
Segment Assets	12,046						12,046		11,979
SCEG | Gas Distribution
Segment Reporting Information [Line Items]
Operating Income	(4)			(2)			44	42
Regulated and Unregulated Operating Revenue				69			304	285
Regulated Operating Revenue	69						303
Segment Assets	909						909		869
SCEG | Adjustments/Eliminations
Segment Reporting Information [Line Items]
Operating Income	0			0			0	0
Regulated and Unregulated Operating Revenue	0			0			0	0
Net Income (Loss) Attributable to Parent	98			$ 39			248	$ 270
Segment Assets	$ 3,174						$ 3,174		$ 3,098