Leases - Maturities of Lease Liabilities (Detail) - USD ($) $ in Millions	Dec. 31, 2021	Dec. 31, 2020
Operating Lease Liabilities, Payments Due [Abstract]
Within one year	$ 12.5	$ 11.4
Year two	9.0	9.4
Year three	6.0	8.2
Year four	3.9	5.5
Year five	3.1	3.8
Thereafter	3.2	4.6
Total lease payments	37.7	42.9
Less imputed interest	(2.2)	(2.7)
Total operating lease liabilities	35.5	40.2
Finance Lease Liabilities, Payments, Due [Abstract]
Within one year	0.1	0.5
Year two	0.0	0.1
Year three	0.0	0.0
Year four	0.0	0.0
Year five	0.0	0.0
Thereafter	0.0	0.0
Total lease payments	0.1	0.6
Less imputed interest	0.0	0.0
Total finance lease liabilities	$ 0.1	$ 0.6