PENSION AND OTHER POST-EMPLOYMENT BENEFIT PLANS - Funded Status of Our Plans (Parenthetical) (Details) - USD ($) $ in Billions	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020
Defined Benefit Plan Disclosure [Line Items]
Pension plans with projected benefit obligations exceeding plan assets, projected benefit obligations	$ 2.9	$ 3.1
Pension plans with projected benefit obligations exceeding plan assets, fair value of assets	2.5	2.3
Pension plans with accumulated benefit obligations exceeding plan assets, accumulated benefit obligations	2.8	3.0
Pension plans with accumulated benefit obligations exceeding plan assets, fair value of assets	$ 2.5	$ 2.3
Pension
Defined Benefit Plan Disclosure [Line Items]
Discount rates, benefit obligation		2.50%
Pension | U.S.
Defined Benefit Plan Disclosure [Line Items]
Discount rates, benefit obligation	2.90%	2.50%
Pension | U.S. | Salaried
Defined Benefit Plan Disclosure [Line Items]
Rate of compensation increase	2.00%
Pension | U.S. | Hourly
Defined Benefit Plan Disclosure [Line Items]
Rate of compensation increase		13.00%
Pension | Canada
Defined Benefit Plan Disclosure [Line Items]
Discount rates, benefit obligation	3.10%	2.50%
Pension | Canada | Salaried
Defined Benefit Plan Disclosure [Line Items]
Rate of compensation increase	3.25%
Pension | Canada | Hourly
Defined Benefit Plan Disclosure [Line Items]
Rate of compensation increase		3.00%
Other Post-employment Benefits | U.S.
Defined Benefit Plan Disclosure [Line Items]
Discount rates, benefit obligation	2.60%	2.10%
Ultimate healthcare cost trend rate	4.50%	4.50%
Year the cost ultimate health care cost rate is reached	2037	2037
Other Post-employment Benefits | U.S. | Pre-Medicare
Defined Benefit Plan Disclosure [Line Items]
Healthcare cost trend rate assumption for next year	6.20%	6.80%
Other Post-employment Benefits | U.S. | Health Reimbursement Account
Defined Benefit Plan Disclosure [Line Items]
Healthcare cost trend rate assumption for next year	4.50%	4.50%
Other Post-employment Benefits | Canada
Defined Benefit Plan Disclosure [Line Items]
Discount rates, benefit obligation	3.00%	2.40%
Healthcare cost trend rate assumption for next year	5.30%	5.30%
Ultimate healthcare cost trend rate	4.00%	4.00%
Year the cost ultimate health care cost rate is reached	2040	2040