PROPERTY, PLANT AND EQUIPMENT (Tables)

12 Months Ended

Dec. 31, 2021

Property, Plant and Equipment [Abstract]

Summary of Carrying Value of Each Major Class of Depreciable Assets

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 27 years

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

	(In Millions)
	December 31,
	2021		2020
Land, land improvements, and mineral rights	$	1,291	$	1,213
Buildings	889		703
Equipment	8,709		6,786
Other	229		151
Construction in progress	408		1,364
Total property, plant and equipment1	11,526		10,217
Allowance for depreciation and depletion	(2,340)		(1,474)
Property, plant, and equipment, net	$	9,186	$	8,743
1 Includes right-of-use assets related to finance leases of $411 million and $361 million as of December 31, 2021 and 2020, respectively.

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

	(In Millions)
	December 31,
	2021		2020
Mineral rights:
Cost	$	780	$	773
Depletion	(187)		(142)
Net mineral rights	$	593	$	631
Land rights	$	406	$	361