INCOME TAXES (Details) - USD ($)	3 Months Ended		9 Months Ended	12 Months Ended
	Mar. 31, 2019	Dec. 31, 2015	Sep. 30, 2015	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Investments, Owned, Federal Income Tax Note [Line Items]
Deferred Tax Assets, Operating Loss Carryforwards				$ 600,000,000
Deferred Tax Asset, Legal Settlement				273,000,000
Unrecognized Tax Benefits, gross of state deduction on federal return and certain operating loss and tax credit carryfowards		$ 49,000,000		98,000,000	$ 350,000,000	$ 49,000,000	$ 16,000,000
Decrease in Unrecognized Tax Benefits is Reasonably Possible				11,000,000
Unrecognized Tax Benefits that Would Impact Effective Tax Rate				$ 98,000,000
Effective Income Tax Rate Reconciliation, State and Local Income Taxes, Percent		5.00%	6.00%	3.00%	4.00%
Effective Income Tax Rate Reconciliation, at Federal Statutory Income Tax Rate, Percent				35.00%
Current Income Tax Expense (Benefit), Continuing Operations [Abstract]
Current Federal Tax Expense (Benefit)				$ (414,000,000)	$ 36,000,000	382,000,000
Current State and Local Tax Expense (Benefit)				18,000,000	13,000,000	57,000,000
Current Income Tax Expense (Benefit)				(396,000,000)	49,000,000	439,000,000
Deferred Income Tax Expense (Benefit), Continuing Operations [Abstract]
Deferred Federal Income Tax Expense (Benefit)				323,000,000	203,000,000	(36,000,000)
Deferred State and Local Income Tax Expense (Benefit)				(37,000,000)	21,000,000	(7,000,000)
Deferred Income Tax Expense (Benefit)				286,000,000	224,000,000	(43,000,000)
Income Tax Reconciliation, Tax Credits, Investment [Abstract]
Amortization of Amounts Deferred Under State and Local Investment Tax Credits				0	0	(1,000,000)
Investment Tax Credit				(2,000,000)	(2,000,000)	(3,000,000)
Income Tax Expense (Benefit)				(112,000,000)	271,000,000	393,000,000
Income (Loss) from Continuing Operations before Income Taxes, Domestic				(231,000,000)	866,000,000	1,139,000,000
Effective Income Tax Rate Reconciliation at Federal Statutory Income Tax Rate, Amount				(81,000,000)	303,000,000	399,000,000
Effective Income Tax Rate Reconciliation, State and Local Income Taxes, Amount				(7,000,000)	27,000,000	38,000,000
Income Tax Reconciliation, Amortization of State and Local Investment Tax Credits				(5,000,000)	(5,000,000)	(6,000,000)
Income Tax Reconciliation, Allowance for Cost of Equity Funds Used During Construction				(8,000,000)	(10,000,000)	(9,000,000)
Effective Income Tax Rate Reconciliation, Deduction, Dividends, Amount				(9,000,000)	(10,000,000)	(10,000,000)
Amortization of Amounts Deferred under Federal Investment Tax Credits				(2,000,000)	(2,000,000)	(2,000,000)
Section 45 tax credit				(8,000,000)	(8,000,000)	(9,000,000)
Effective Income Tax Rate Reconciliation, Deduction, Qualified Production Activity, Percent				(18,000,000)	(23,000,000)	(18,000,000)
Income Tax Reconcilation, Tax Reform Remeasurement				30,000,000
Income Tax Reconciliation, Sale of Subsidiaries				0	0	7,000,000
Effective Income Tax Rate Reconciliation, Other Adjustments, Amount				(4,000,000)	(1,000,000)	3,000,000
Deferred Tax Assets, Tax Deferred Expense, Reserves and Accruals, Accrued Liabilities				88,000,000	148,000,000
Deferred tax Nuclear Decommissioning				141,000,000	213,000,000
Deferred Tax Asset, Remeasurement				54,000,000
Deferred Tax Assets, Financial Instruments				15,000,000	22,000,000
Deferred Tax Asset, Unamortized Investment, Tax Credits				8,000,000	15,000,000
Deferred Tax Asset, Deferred Fuel Cost					17,000,000
Deferred Tax Assets, Other				6,000,000	10,000,000
Deferred Tax Assets, Net				1,185,000,000	425,000,000
Deferred Tax Liabilities, Property, Plant and Equipment				1,220,000,000	2,159,000,000
Deferred Tax Liability, Impairment				962,000,000
Deferred Tax Liabilities, Tax Deferred Expense Compensation and Benefits, Employee Benefits				60,000,000	105,000,000
Deferred Tax Liabilities, Asset Retirement Obligation				91,000,000	143,000,000
Deferred tax asset unrecovered plant				27,000,000	45,000,000
Deferred Tax Liability, Demand Side Management				16,000,000	23,000,000
deferred tax liability, prepayments				21,000,000	32,000,000
Deferred Tax Liabilities, Other				49,000,000	77,000,000
Deferred Tax Liabilities, Net				2,446,000,000	2,584,000,000
Deferred Tax Liabilities, Net, Noncurrent				1,261,000,000	2,159,000,000
Unrecognized tax benefits				19,000,000	219,000,000
Unrecognized Tax Benefits, Increase Resulting from Prior Period Tax Positions				0	94,000,000	33,000,000
Unrecognized Tax Benefits, Decrease Resulting from Prior Period Tax Positions				(273,000,000)	0	(2,000,000)
Unrecognized Tax Benefits, Increase Resulting from Current Period Tax Positions				21,000,000	207,000,000	2,000,000
SCE&G
Investments, Owned, Federal Income Tax Note [Line Items]
Deferred Tax Assets, Operating Loss Carryforwards				541,000,000
Deferred Tax Asset, Legal Settlement				273,000,000
Unrecognized Tax Benefits, gross of state deduction on federal return and certain operating loss and tax credit carryfowards		$ 49,000,000		98,000,000	350,000,000	49,000,000	$ 16,000,000
Decrease in Unrecognized Tax Benefits is Reasonably Possible				11,000,000
Unrecognized Tax Benefits that Would Impact Effective Tax Rate				98,000,000
Increase in Unrecognized Tax Benefits is Reasonably Possible				0
Unrecognized Tax Benefits, Interest Income on Taxes Accrued				0
Unrecognized Tax Benefits, Interest on Income Taxes Accrued				0
Unrecognized Tax Benefits, Income Tax Penalties Expense				0
Current Income Tax Expense (Benefit), Continuing Operations [Abstract]
Current Federal Tax Expense (Benefit)				(410,000,000)	50,000,000	208,000,000
Current State and Local Tax Expense (Benefit)				(18,000,000)	13,000,000	32,000,000
Current Income Tax Expense (Benefit)				(428,000,000)	63,000,000	240,000,000
Deferred Income Tax Expense (Benefit), Continuing Operations [Abstract]
Deferred Federal Income Tax Expense (Benefit)				261,000,000	167,000,000	(3,000,000)
Deferred State and Local Income Tax Expense (Benefit)				2,000,000	20,000,000	(3,000,000)
Deferred Income Tax Expense (Benefit)				(259,000,000)	187,000,000	(6,000,000)
Income Tax Reconciliation, Tax Credits, Investment [Abstract]
Amortization of Amounts Deferred Under State and Local Investment Tax Credits				0	0	(1,000,000)
Investment Tax Credit				(2,000,000)	(2,000,000)	(3,000,000)
Income Tax Expense (Benefit)				(171,000,000)	248,000,000	231,000,000
Income (Loss) from Continuing Operations before Income Taxes, Domestic				(343,000,000)	774,000,000	711,000,000
Effective Income Tax Rate Reconciliation at Federal Statutory Income Tax Rate, Amount				(120,000,000)	271,000,000	249,000,000
Effective Income Tax Rate Reconciliation, State and Local Income Taxes, Amount				(8,000,000)	26,000,000	24,000,000
Income Tax Reconciliation, Amortization of State and Local Investment Tax Credits				(5,000,000)	(5,000,000)	(6,000,000)
Income Tax Reconciliation, Allowance for Cost of Equity Funds Used During Construction				(5,000,000)	(9,000,000)	(9,000,000)
Amortization of Amounts Deferred under Federal Investment Tax Credits				(2,000,000)	(2,000,000)	(2,000,000)
Section 45 tax credit				(8,000,000)	(8,000,000)	(9,000,000)
Effective Income Tax Rate Reconciliation, Deduction, Qualified Production Activity, Percent				(18,000,000)	(23,000,000)	(18,000,000)
Income Tax Reconcilation, Tax Reform Remeasurement				(1,000,000)
Effective Income Tax Rate Reconciliation, Other Adjustments, Amount				(4,000,000)	(2,000,000)	2,000,000
Deferred Tax Assets, Tax Deferred Expense, Reserves and Accruals, Accrued Liabilities				42,000,000	53,000,000
Deferred tax Nuclear Decommissioning				132,000,000	200,000,000
Deferred Tax Asset, Remeasurement				54,000,000
Deferred Tax Asset, Unamortized Investment, Tax Credits				8,000,000	15,000,000
Deferred Tax Asset, Deferred Fuel Cost					17,000,000
Deferred Tax Assets, Other				5,000,000	8,000,000
Deferred Tax Assets, Net				1,055,000,000	293,000,000
Deferred Tax Liabilities, Property, Plant and Equipment				1,035,000,000	1,856,000,000
Deferred Tax Liability, Impairment				962,000,000
Deferred Tax Liabilities, Tax Deferred Expense Compensation and Benefits, Employee Benefits				53,000,000	93,000,000
Deferred Tax Liabilities, Asset Retirement Obligation				85,000,000	135,000,000
Deferred tax asset unrecovered plant				27,000,000	45,000,000
Deferred Tax Liability, Demand Side Management				16,000,000	23,000,000
deferred tax liability, prepayments				19,000,000	30,000,000
Deferred Tax Liabilities, Other				31,000,000	50,000,000
Deferred Tax Liabilities, Net				2,228,000,000	2,232,000,000
Deferred Tax Liabilities, Net, Noncurrent				1,173,000,000	1,939,000,000
Unrecognized tax benefits				19,000,000	236,000,000
Unrecognized Tax Benefits, Increase Resulting from Prior Period Tax Positions				0	94,000,000	33,000,000
Unrecognized Tax Benefits, Decrease Resulting from Prior Period Tax Positions				(273,000,000)	0	(2,000,000)
Unrecognized Tax Benefits, Increase Resulting from Current Period Tax Positions				$ 21,000,000	$ 207,000,000	$ 2,000,000
Income Tax Authority [Domain]
Investments, Owned, Federal Income Tax Note [Line Items]
Effective Income Tax Rate Reconciliation, State and Local Income Taxes, Percent	2.50%