Derivatives - Schedule of Fair Value of Derivatives Designated and Not Designated as Hedges (Detail) - Not Designated as Hedging Instrument - USD ($) $ in Millions	Dec. 31, 2017	Dec. 31, 2016
Prepaid Expenses and Other Current Assets
Derivatives Fair Value [Line Items]
Derivatives assets	$ 2.2	$ 1.7
Accrued Liabilities
Derivatives Fair Value [Line Items]
Derivatives liabilities		$ 1.5