Summary of Significant Accounting Policies (Tables)

12 Months Ended

Dec. 31, 2021

The components of inventories were as follows (dollars in millions):


	December 31,
	2021		2020
Raw materials	$	324.2	$	263.5
Work in process		16.2		11.6
Finished goods		201.0		183.6
Supplies and materials		361.1		329.2
Inventories	$	902.5	$	787.9

Property, Plant and Equipment (at cost)

Property, plant, and equipment consisted of the following (dollars in millions):


	December 31,
	2021			2020
Land and land improvements	$	189.8		$	179.6
Buildings		938.7			858.5
Machinery and equipment		6,159.1			5,826.6
Construction in progress		481.0			360.0
Other		102.9			88.8
Property, plant and equipment, at cost		7,871.5			7,313.5
Less accumulated depreciation		(4,342.5	)		(4,120.1	)
Property, plant and equipment, net	$	3,529.0		$	3,193.4

Property, Plant and Equipment Estimated Useful Lives

Depreciation is computed on the straight-line basis over the estimated useful lives of the related assets. Assets under finance leases are depreciated on the straight-line method over the term of the lease or the useful life, if shorter. The following lives are used for the various categories of assets:


Buildings and land improvements		5 to 40 years
Machinery and equipment		3 to 25 years
Trucks and automobiles		3 to 10 years
Furniture and fixtures		3 to 20 years
Computers and hardware		3 to 10 years
Leasehold improvements		Period of the lease or useful life, if shorter