PROPERTY AND EQUIPMENT, NET - Carrying Value of Property and Equipment and Estimated Service Lives (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
Property and Equipment [Line Items]
Property and equipment, at cost	$ 5,445	$ 5,446
Accumulated depreciation and amortization	(3,432)	(3,477)
Property and equipment, net	2,013	1,969
Land
Property and Equipment [Line Items]
Property and equipment, at cost	84	87
Buildings and improvements
Property and Equipment [Line Items]
Property and equipment, at cost	$ 1,049	999
Buildings and improvements | Minimum
Property and Equipment [Line Items]
Estimated service lives	15 years
Buildings and improvements | Maximum
Property and Equipment [Line Items]
Estimated service lives	40 years
Machinery and Equipment
Property and Equipment [Line Items]
Property and equipment, at cost	$ 3,486	3,425
Machinery and Equipment | Minimum
Property and Equipment [Line Items]
Estimated service lives	5 years
Machinery and Equipment | Maximum
Property and Equipment [Line Items]
Estimated service lives	25 years
Roads
Property and Equipment [Line Items]
Property and equipment, at cost	$ 725	742
Roads | Minimum
Property and Equipment [Line Items]
Estimated service lives	10 years
Roads | Maximum
Property and Equipment [Line Items]
Estimated service lives	35 years
Other
Property and Equipment [Line Items]
Property and equipment, at cost	$ 101	$ 193
Other | Minimum
Property and Equipment [Line Items]
Estimated service lives	3 years
Other | Maximum
Property and Equipment [Line Items]
Estimated service lives	10 years