Leases - Schedule of Cash Flow Items are Included on Condensed Consolidated Statement of Cash Flows (Detail) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020
Leases [Abstract]
Operating cash used for operating leases	$ 3.0	$ 3.1	$ 9.1	$ 9.6
Operating cash used for finance leases	0.1		0.1	0.1
Financing cash used for finance leases	$ 0.4	$ 0.4	$ 1.2	$ 1.1