Derivatives - Summary of (Loss) Gain on Derivatives Designated as Cash Flow Hedging Instruments (Detail) - Cash Flow Hedging [Member] - Foreign Exchange Forward Contracts [Member] - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Derivative Instruments, Gain (Loss) [Line Items]
Net (loss) gain recognized in OCI, net of tax	$ (10.6)	$ (10.0)	$ 4.9
Net gain reclassified from OCI into income	$ 1.7	$ 5.7	$ 3.4