Revenue Recognition - Summary of Opening and Closing Balances of Contract Liability and Accounts Receivable (Detail) - USD ($) $ in Millions	6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019
Disaggregation Of Revenue [Line Items]
Accounts Receivable, Beginning Balance	$ 243.2
Accounts Receivable, Closing Balance	230.6
ASU 2014-09 [Member]
Disaggregation Of Revenue [Line Items]
Deferred Revenue (Current), Beginning Balance	8.4	$ 7.4
Deferred Revenue (Current), Closing Balance	12.5	8.1
Deferred Revenue (Current), Increase/(Decrease)	4.1	0.7
Accounts Receivable, Beginning Balance	243.2	259.8
Accounts Receivable, Closing Balance	230.6	269.6
Accounts Receivable, Increase/(Decrease)	$ (12.6)	$ 9.8