Derivative Instruments - Derivatives Designated as Hedging Instruments by Classification and Amount of Gains and Losses (Detail) - Designated As Hedging Instrument - Foreign currency forward exchange contracts - USD ($) $ in Thousands	12 Months Ended
Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Derivative Instruments, Gain (Loss) [Line Items]
Amount of (loss) gain recognized in OCI	$ (55,377)	$ 18,733	$ 37,926
Cost of sales
Derivative Instruments, Gain (Loss) [Line Items]
Amount of (loss) gain reclassified from accumulated OCI to the consolidated statements of operations	$ (16,810)	$ 16,627	$ 52,588

Derivative Instruments - Derivatives Designated as Hedging Instruments by Classification and Amount of Gains and Losses (Detail) - Designated As Hedging Instrument - Foreign currency forward exchange contracts - USD ($)
$ in Thousands

12 Months Ended

Dec. 31, 2017

Dec. 31, 2016

Dec. 31, 2015

Derivative Instruments, Gain (Loss) [Line Items]

Amount of (loss) gain recognized in OCI

$ (55,377)

$ 18,733

$ 37,926

Cost of sales

Derivative Instruments, Gain (Loss) [Line Items]

Amount of (loss) gain reclassified from accumulated OCI to the consolidated statements of operations

$ (16,810)

$ 16,627

$ 52,588