Financial Derivatives and Hedging Activities - Fair Values of Derivative Instruments (Detail) - Forward Foreign Currency Exchange Contracts [Member] - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Designated as Hedging [Member] | Prepaid Expenses and Other Current Assets [Member]
Derivatives Fair Value [Line Items]
Derivative asset, fair value	$ 1,066	$ 2,625
Designated as Hedging [Member] | Other Current Liabilities [Member]
Derivatives Fair Value [Line Items]
Derivative liability, fair value	4,787	1,493
Not Designated as Hedging [Member] | Prepaid Expenses and Other Current Assets [Member]
Derivatives Fair Value [Line Items]
Derivative asset, fair value	151	60
Not Designated as Hedging [Member] | Other Current Liabilities [Member]
Derivatives Fair Value [Line Items]
Derivative liability, fair value	$ 43	$ 104