Schedule of Cash Flow Information Related to Leases (Detail) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
Cash paid for amounts included in the measurement of lease liabilities
Operating cash flows from operating leases	$ 17.2	$ 17.0
Operating cash flows from finance leases	0.1	0.2
Financing cash flows from finance leases	0.9	1.0
Right-of-use assets obtained in exchange for lease liabilities
Operating leases	19.9	8.9
Finance leases	$ 0.5	$ 0.7