Leases - Lease expense (Detail) - USD ($) $ in Millions		3 Months Ended
		Mar. 31, 2020	Mar. 31, 2019
Lease Cost:
Operating lease cost(1)	[1]	$ 7.3	$ 5.0
Short-term lease		1.2	1.3
Total lease cost		$ 8.5	$ 6.3

[1] Operating lease cost includes an immaterial amount of variable expenses and sublease rental income