EMPLOYEE BENEFIT PLANS (Change in Projected Benefit Obligation and Plan Assets and Reconciliation of Funded Status) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Pension Benefits
Change in Projected Benefit Obligation
Beginning of Period	$ 424	$ 394
Actuarial Loss	42	20
Interest Cost	15	15	$ 17
Service Cost	13	12	12
Benefits Paid	(19)	(17)
End of Period	475	424	394
Change in Fair Value of Plan Assets
Beginning of Period	354	336
Actual Return on Plan Assets	59	27
Benefits Paid	(19)	(17)
Employer Contributions	9	8
End of Period	403	354	336
Funded Status at End of Period	(72)	(70)
Other Postretirement Benefits
Change in Projected Benefit Obligation
Beginning of Period	79	78
Actuarial Loss	1	0
Interest Cost	2	2	3
Service Cost	4	4	4
Benefits Paid	(4)	(5)
End of Period	82	79	78
Change in Fair Value of Plan Assets
Beginning of Period	14	13
Actual Return on Plan Assets	2	1
Benefits Paid	(4)	(5)
Employer Contributions	5	5
End of Period	17	14	$ 13
Funded Status at End of Period	$ (65)	$ (65)