Leases - Components of Lease Expense (Detail) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020
Finance lease cost:
Amortization of right-of-use assets	$ 0.5	$ 1.0
Interest on lease liabilities	0.0	0.0
Total finance lease cost	0.5	1.0
Operating lease cost	13.8	12.8
Short-term lease cost	3.8	3.2
Variable lease cost	0.3	0.3
Total lease cost	$ 18.4	$ 17.3