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, 2019	Dec. 31, 2018
Pension Benefits
Pension And Other Employee Benefit Plans [Line Items]
Net (Gain) Loss	$ 145	$ 133
Prior Service Cost (Benefit)	0	0
Other Postretirement Benefits
Pension And Other Employee Benefit Plans [Line Items]
Net (Gain) Loss	1	(1)
Prior Service Cost (Benefit)	$ (2)	$ (2)