EMPLOYEE BENEFIT PLANS (Components of Regulatory Assets and Accumulated Other Comprehensive Loss Not Recognized as Net Periodic Benefit Cost) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017
Pension Benefits
Pension And Other Employee Benefit Plans [Line Items]
Net (Gain) Loss	$ 133	$ 129
Prior Service Cost (Benefit)	0	1
Other Postretirement Benefits
Pension And Other Employee Benefit Plans [Line Items]
Net (Gain) Loss	(1)	5
Prior Service Cost (Benefit)	$ (2)	$ (1)