PROPERTY, PLANT AND EQUIPMENT (Tables)

12 Months Ended

Dec. 31, 2020

Property, Plant and Equipment [Abstract]

Property Plant and Equipment [Table Text Block]

Depreciation and depletion are recorded over the following estimated useful lives:

Asset Class	Basis	Life
Land, land improvements and mineral rights
Land and mineral rights	Units of production	Life of mine
Land improvements	Straight line	20 to 45 years
Buildings	Straight line	20 to 45 years
Equipment	Straight line/Double declining balance	3 to 20 years

The following table indicates the carrying value of each of the major classes of our depreciable assets:

	(In Millions)
	December 31,
	2020		2019
Land, land improvements, and mineral rights	$	1,213	$	582
Buildings	703		158
Equipment	6,786		1,456
Other	151		101
Construction in progress	1,364		730
Total property, plant and equipment1	10,217		3,027
Allowance for depreciation and depletion	(1,474)		(1,098)
Property, plant, and equipment, net	$	8,743	$	1,929
1 Includes right-of-use assets related to finance leases of $361 million and $49 million as of December 31, 2020 and 2019, respectively.

The net book value of the mineral and land rights are as follows:

	(In Millions)
	December 31,
	2020		2019
Mineral rights:
Cost	$	773	$	537
Depletion	(142)		(134)
Net mineral rights	$	631	$	403
Land rights	$	361	$	12