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] - USD ($)	Sep. 30, 2017	Dec. 31, 2016
Prepaid Expenses and Other Current Assets [Member]
Derivatives, Fair Value [Line Items]
Derivative Notional Amount	$ 10,874,000	$ 60,756,000
Derivative Fair Value	$ 1,161,000
Accrued and Other Current Liabilities [Member]
Derivatives, Fair Value [Line Items]
Derivative Fair Value		$ (639,000)