PROPERTY AND EQUIPMENT - Carrying Value of Property and Equipment and Estimated Service Lives (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018
Property and Equipment [Line Items]
Property and equipment, at cost	$ 5,446	$ 5,233
Accumulated depreciation and amortization	(3,477)	(3,376)
Property and equipment, net	1,969	1,857
Land
Property and Equipment [Line Items]
Property and equipment, at cost	87	87
Buildings and improvements
Property and Equipment [Line Items]
Property and equipment, at cost	$ 999	942
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	$ 3,425	3,240
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	$ 742	785
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	$ 193	$ 179
Other | Minimum
Property and Equipment [Line Items]
Estimated service lives	3 years
Other | Maximum
Property and Equipment [Line Items]
Estimated service lives	10 years