Fair Value Measurement - Additional Information (Detail) $ in Millions	3 Months Ended
	Mar. 31, 2018 USD ($) Contract	Mar. 31, 2017 USD ($)	Dec. 31, 2017 USD ($)
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Fair value of earn-out liability		$ 14.0	$ 14.0
Other operating income from earn out liability adjustment	$ 14.0	13.0
Derivatives Designated as Hedging Instruments
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Gains and losses reclassified from OCI and recognized in Consolidated Statements of Income, net	(0.5)	1.5
Gains or losses expected to be reclassified from OCI and recognized in consolidated statements of income within the next twelve months	0.4
Not Designated as Hedging Instrument
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Gains and losses recognized in other non-operating items, net	$ (1.5)	(1.4)
Foreign Exchange Swaps
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Number of Foreign Currency Derivatives Held | Contract	0
Foreign Exchange Swaps | Maximum
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Maturity Period of Swap Contracts	6 months
Foreign Exchange Forward | Derivatives Designated as Hedging Instruments | Cash Flow Hedging
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Gain (loss) recognized in consolidated statements of income	$ 0.0	$ 1.0