EMPLOYEE BENEFIT PLANS (Pension and Other Postretirement Benefit Amounts included in Consolidated Balance Sheet ) (Details) - USD ($) $ in Millions	Dec. 31, 2019	Dec. 31, 2018
Pension And Other Employee Benefit Plans [Line Items]
Regulatory Assets	$ 465	$ 400
Regulatory Liabilities	(573)	(607)
Pension Benefits
Pension And Other Employee Benefit Plans [Line Items]
Regulatory Assets	135	126
Regulatory Liabilities	0	0
Accrued Employee Expenses	(2)	(1)
Pension and Other Postretirement Benefits	(77)	(63)
Accumulated Other Comprehensive Loss, SERP	10	6
Net Amount Recognized	66	68
Other Postretirement Benefits
Pension And Other Employee Benefit Plans [Line Items]
Regulatory Assets	0	0
Regulatory Liabilities	(1)	(3)
Accrued Employee Expenses	(2)	(3)
Pension and Other Postretirement Benefits	(56)	(54)
Accumulated Other Comprehensive Loss, SERP	0	0
Net Amount Recognized	$ (59)	$ (60)