PENSION AND OTHER POSTRETIREMENT BENEFIT PLANS Additional Information (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Jun. 30, 2018	Sep. 30, 2018
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Plan Assets, Period Increase (Decrease)		$ 44
Defined Benefit Plan, Benefit Obligation, Period Increase (Decrease)		(155)
Defined Benefit Plan Funded Status Period Increase (Decrease)		$ 199
Registered Canadian Pension Plan
Defined Benefit Plan Disclosure [Line Items]
Expected contribution to benefit plans during 2018	$ 24		$ 24
Non Registered Canadian Pension Plans
Defined Benefit Plan Disclosure [Line Items]
Expected contribution to benefit plans during 2018	2		2
U.S. Non-Qualified Pension Plans
Defined Benefit Plan Disclosure [Line Items]
Expected contribution to benefit plans during 2018	19		19
U.S. Qualified Pension Plans
Defined Benefit Plan Disclosure [Line Items]
Pension Contribution	300		300
U.S. and Canadian Other Postretirement Plans
Defined Benefit Plan Disclosure [Line Items]
Expected contribution to benefit plans during 2018	$ 19		$ 19