Leases - Schedule of Maturities of lease liabilities (Detail) $ in Millions	Sep. 30, 2019 USD ($)
Finance Lease Liabilities, Payments, Due [Abstract]
2019	$ 0.5
2020	1.5
2021	1.4
2022	1.0
2023	0.6
Total lease payments	5.0
Less: imputed interest	(0.7)
Total future lease obligation	4.3
Operating Lease Liabilities, Payments Due [Abstract]
2019	3.2
2020	11.0
2021	9.0
2022	6.8
2023	5.9
Thereafter	11.3
Total lease payments	47.2
Less: imputed interest	(7.1)
Total future lease obligation	$ 40.1