Revenue Recognition - Summary of Opening and Closing Balances of Contract Liability and Receivables (Detail) $ in Millions	3 Months Ended
	Mar. 31, 2019 USD ($)
Disaggregation Of Revenue [Line Items]
Accounts Receivable, Beginning Balance	$ 259.8
Accounts Receivable, Closing Balance	281.8
ASU 2014-09 [Member]
Disaggregation Of Revenue [Line Items]
Deferred Revenue (Current), Beginning Balance	7.4
Deferred Revenue (Current), Closing Balance	7.8
Deferred Revenue (Current), Increase/(Decrease)	0.4
Accounts Receivable, Beginning Balance	259.8
Accounts Receivable, Closing Balance	281.8
Accounts Receivable, Increase/(Decrease)	$ 22.0