PENSION AND OTHER POSTRETIREMENT BENEFIT PLANS - Assumptions We Use in Estimating Health Care Benefit Costs (Details)	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015
U.S.
Defined Benefit Plan Disclosure [Line Items]
Rate to which cost trend rate is assumed to decline (ultimate trend rate)	4.50%	4.50%
Year that the rate reaches the ultimate trend rate	2037	2036
U.S. | Pre Medicare
Defined Benefit Plan Disclosure [Line Items]
Weighted health care cost trend rate assumed for next year	8.90%	7.20%
U.S. | Health Reimbursement Account
Defined Benefit Plan Disclosure [Line Items]
Weighted health care cost trend rate assumed for next year	4.50%	4.50%
Canada
Defined Benefit Plan Disclosure [Line Items]
Weighted health care cost trend rate assumed for next year	4.90%	5.00%
Rate to which cost trend rate is assumed to decline (ultimate trend rate)	4.30%	4.30%
Year that the rate reaches the ultimate trend rate	2028	2028