EMPLOYEE BENEFIT PLANS (Changes in Regulatory Assets and Accumulated Comprehensive Income) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Pension Plan [Member] | Regulatory Asset [Member]
Pension Plans, Postretirement and Other Employee Benefits [Line Items]
Current Year Actuarial (Gain) Loss	$ 15	$ 5	$ 49
Amortization of Net Loss	(7)	(7)	(3)
Total Recognized (Gain) Loss	8	(2)	46
Pension Plan [Member] | Accumulated Other Comprehensive Loss [Member]
Pension Plans, Postretirement and Other Employee Benefits [Line Items]
Current Year Actuarial (Gain) Loss	1	0	3
Amortization of Net Loss	0	0	0
Total Recognized (Gain) Loss	1	0	3
Other Postretirement Benefits [Member] | Regulatory Asset [Member]
Pension Plans, Postretirement and Other Employee Benefits [Line Items]
Current Year Actuarial (Gain) Loss	0	(4)	5
Amortization of Net Loss	0	0	0
Total Recognized (Gain) Loss	$ 0	$ (4)	$ 5