EMPLOYEE BENEFIT PLANS (Pension and Other Postretirement Benefit Amounts included in Consolidated Balance Sheet ) (Details) - USD ($) $ in Millions	Dec. 31, 2018	Dec. 31, 2017
Pension And Other Employee Benefit Plans [Line Items]
Regulatory Assets	$ 400	$ 388
Regulatory Liabilities	(607)	(605)
Pension Benefits
Pension And Other Employee Benefit Plans [Line Items]
Regulatory Assets	126	121
Regulatory Liabilities	0	0
Accrued Employee Expenses	(1)	(1)
Pension and Other Postretirement Benefits	(63)	(71)
Accumulated Other Comprehensive Loss, SERP	6	9
Net Amount Recognized	68	58
Other Postretirement Benefits
Pension And Other Employee Benefit Plans [Line Items]
Regulatory Assets	0	5
Regulatory Liabilities	(3)	0
Accrued Employee Expenses	(3)	(2)
Pension and Other Postretirement Benefits	(54)	(63)
Accumulated Other Comprehensive Loss, SERP	0	0
Net Amount Recognized	$ (60)	$ (60)