PENSION AND OTHER POSTRETIREMENT BENEFIT PLANS - Discount Rates and Rates of Compensation Increase Used in Estimating Our Pension and Other Postretirement Benefit Obligation (Details)	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014
United States Pension Plans
Defined Benefit Plan Disclosure [Line Items]
Discount rates	4.50%	4.10%
United States Other Postretirement Benefit Plans
Defined Benefit Plan Disclosure [Line Items]
Discount rates	4.00%	3.60%
Canadian Pension Plans
Defined Benefit Plan Disclosure [Line Items]
Discount rates	4.00%	3.90%
Canadian Other Postretirement Benefit Plans
Defined Benefit Plan Disclosure [Line Items]
Discount rates	3.90%	3.80%
Pension
Defined Benefit Plan Disclosure [Line Items]
Election of lump sum or installment distributions (US salaried and nonqualified plans only)	60.00%	60.00%
Salaried | United States Pension Plans
Defined Benefit Plan Disclosure [Line Items]
Rate of compensation increase, current year	2.00%	2.50%
Rate of compensation increase, thereafter	13.00%	3.50%
Salaried | Canadian Pension Plans
Defined Benefit Plan Disclosure [Line Items]
Rate of compensation increase, current year	2.50%	2.50%
Rate of compensation increase, thereafter	3.50%	3.50%
Hourly | United States Pension Plans
Defined Benefit Plan Disclosure [Line Items]
Rate of compensation increase		3.00%
Hourly | Canadian Pension Plans
Defined Benefit Plan Disclosure [Line Items]
Rate of compensation increase	3.25%	3.25%
Minimum | Hourly | United States Pension Plans
Defined Benefit Plan Disclosure [Line Items]
Rate of compensation increase	2.30%
Maximum | Hourly | United States Pension Plans
Defined Benefit Plan Disclosure [Line Items]
Rate of compensation increase	13.00%