PENSION AND OTHER POSTRETIREMENT BENEFIT PLANS - Effect of a One Percent Change in Health Care Costs (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016
Defined Benefit Plan Disclosure [Line Items]
Effect on total service and interest cost components on 1 percent increase in health care costs (less than)	$ 1
Effect on total service and interest cost components on 1 percent decrease in health care costs (less than)		$ (1)
Effect on accumulated postretirement benefit obligation on 1 percent increase in health care costs	7
Effect on accumulated postretirement benefit obligation on 1 percent decrease in health care costs	$ (7)