PENSION AND OTHER POSTRETIREMENT BENEFIT PLANS - Assumptions We Use in Estimating Health Care Benefit Costs (Details)	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018
U.S.
Defined Benefit Plan Disclosure [Line Items]
Rate that the cost trend rate gradually declines to	4.50%	4.50%
Year the cost trend rate is reached	2037	2037
Canada
Defined Benefit Plan Disclosure [Line Items]
Weighted health care cost trend rate assumed for next year	5.40%	4.90%
Rate that the cost trend rate gradually declines to	4.00%	4.00%
Year the cost trend rate is reached	2039	2039
Pre Medicare | U.S.
Defined Benefit Plan Disclosure [Line Items]
Weighted health care cost trend rate assumed for next year	7.30%	7.80%
Health Reimbursement Account | U.S.
Defined Benefit Plan Disclosure [Line Items]
Weighted health care cost trend rate assumed for next year	4.50%	4.50%