Property, Plant And Equipment (Tables)

12 Months Ended

Dec. 31, 2020

Property, Plant and Equipment [Abstract]

Schedule of Property, Plant and Equipment

The provision for depreciation has been computed principally by the straight-line method based on the estimated useful lives of the depreciable assets as follows:

Category	Useful Life
Buildings	30 years
Leased assets and leasehold improvements	Amortized over the lesser of the economic life of the asset or the term of the lease
Machinery, equipment and other assets	3 – 10 years

The classes of property, plant and equipment as of December 31 are summarized as follows ($ in millions):

	2020		2019
Land and improvements	$	24.8	$	23.7
Buildings and improvements	182.6		166.9
Machinery, equipment and other assets	438.8		410.1
Construction in progress	84.8		92.2
Gross property, plant and equipment	731.0		692.9
Less: accumulated depreciation	(428.0)		(402.6)
Property, plant and equipment, net	$	303.0	$	290.3