PENSION AND OTHER POSTRETIREMENT BENEFIT PLANS - Assets Within Our U.S. and Canadian Qualified and Registered Pension Plans (Details) - Qualified and Registered Plans	Dec. 31, 2019	Dec. 31, 2018
Defined Benefit Plan Disclosure [Line Items]
Assets invested in pension plan, allocation percentage	100.00%	100.00%
Cash and short-term investments
Defined Benefit Plan Disclosure [Line Items]
Assets invested in pension plan, allocation percentage	3.20%	5.80%
Fixed income investments, Corporate
Defined Benefit Plan Disclosure [Line Items]
Assets invested in pension plan, allocation percentage	33.90%	21.50%
Government
Defined Benefit Plan Disclosure [Line Items]
Assets invested in pension plan, allocation percentage	25.40%	8.60%
Fixed Income Investments, Repurchase Agreements
Defined Benefit Plan Disclosure [Line Items]
Repurchase agreements	(4.70%)	0.00%
Hedge funds and related investments
Defined Benefit Plan Disclosure [Line Items]
Assets invested in pension plan, allocation percentage	14.30%	36.90%
Public equity investments
Defined Benefit Plan Disclosure [Line Items]
Assets invested in pension plan, allocation percentage	0.10%	0.00%
Private equity and related investments
Defined Benefit Plan Disclosure [Line Items]
Assets invested in pension plan, allocation percentage	27.70%	21.90%
Derivative instruments, net
Defined Benefit Plan Disclosure [Line Items]
Assets invested in pension plan, allocation percentage	0.30%	5.60%
Accrued liabilities
Defined Benefit Plan Disclosure [Line Items]
Repurchase agreements	(0.20%)	(0.30%)