Leases - Components of Lease Expense (Detail) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Lease Cost
Operating lease cost	$ 2.3	$ 4.0
Financing lease cost:
Depreciation of lease assets	0.2
Interest on lease liabilities	0.1
Sublease income	(1.0)	(1.2)
Total lease cost, net	$ 1.6	$ 2.8