Property, Plant and Equipment - Schedule of company's property, plant and equipment net (Detail) - USD ($) $ in Millions	Dec. 31, 2021	Sep. 30, 2021	Dec. 31, 2020
Property, Plant and Equipment [Line Items]
Property, Plant and Equipment, Gross	$ 874.5		$ 891.7
Less: accumulated depreciation	(438.0)		(440.7)
Total Property, Plant and Equipment, Net	436.5	$ 451.0	451.0
Land [Member]
Property, Plant and Equipment [Line Items]
Property, Plant and Equipment, Gross	3.4		3.6
Building [Member]
Property, Plant and Equipment [Line Items]
Property, Plant and Equipment, Gross	120.1		120.4
Machinery and Equipment [Member]
Property, Plant and Equipment [Line Items]
Property, Plant and Equipment, Gross	559.5		570.8
Leasehold Improvements [Member]
Property, Plant and Equipment [Line Items]
Property, Plant and Equipment, Gross	6.5		6.1
Construction in Progress [Member]
Property, Plant and Equipment [Line Items]
Property, Plant and Equipment, Gross	$ 185.0		$ 190.8