Financial Assets and Liabilities Measured at Fair Value on Recurring Basis (Parenthetical) (Detail) - Not Designated as Hedging Instrument - Foreign Exchange Swaps - Fair Value, Measurements, Recurring - Less Than Six Months - USD ($) $ in Millions	Sep. 30, 2017	Dec. 31, 2016
Derivatives, Fair Value [Line Items]
Derivative notional volume, amount after offsetting swaps	$ 395.4	$ 226.5
Other current assets
Derivatives, Fair Value [Line Items]
Derivative asset, amount after offsetting swaps	1.0	1.1
Other current liabilities
Derivatives, Fair Value [Line Items]
Derivative liability, amount after offsetting swaps	$ 0.4	$ 0.0