EMPLOYEE BENEFITS - Assumptions Used in Determining the Net Periodic Benefit Cost of the Postretirement Benefits Plan (Details) - Postretirement Benefit Plan - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Discount rate	3.53%	3.93%
Ultimate health care cost trend rate	5.00%	5.00%
Effect on accumulated postretirement benefit obligation: One percent increase in assumed health care cost trend	$ 0	$ 0
Effect on accumulated postretirement benefit obligation: One percent decrease in assumed health care cost trend	$ 0	$ 0