Derivative Instruments - Derivative Instruments Measured at Fair Value and Classification on Condensed Consolidated Balance Sheets (Detail) - Forward Foreign Exchange Contracts [Member] - Designated As Hedging Instrument [Member] - Prepaid Expenses and Other Current Assets [Member] - USD ($)	Mar. 31, 2018	Dec. 31, 2017
Derivatives, Fair Value [Line Items]
Derivative Notional Amount	$ 48,495,000	$ 66,560,000
Derivative Fair Value	$ 175,000	$ 551,000