PENSION AND OTHER POSTRETIREMENT BENEFIT PLANS Additional Information (Details) $ in Millions	Mar. 31, 2018 USD ($)
U.S. and Canadian Other Postretirement Plans
Defined Benefit Plan Disclosure [Line Items]
Expected contribution to benefit plans during 2018	$ 19
Registered Canadian Pension Plan
Defined Benefit Plan Disclosure [Line Items]
Expected contribution to benefit plans during 2018	23
Non Registered Canadian Pension Plans
Defined Benefit Plan Disclosure [Line Items]
Expected contribution to benefit plans during 2018	4
U.S. Non-Qualified Pension Plans
Defined Benefit Plan Disclosure [Line Items]
Expected contribution to benefit plans during 2018	19
U.S. Qualified Pension Plans
Defined Benefit Plan Disclosure [Line Items]
Expected contribution to benefit plans during 2018	$ 0