Fair Value Measurements - Gains and Losses on Derivative Instruments in Consolidated Statement of Operations (Detail) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Other non-operating (expense) income | Not designated as hedging instruments: | Foreign Exchange Contracts
Derivative Instruments, Gain (Loss) [Line Items]
Amount of (Loss) Gain Recognized in Income on Derivatives	$ (1,448)	$ 330	$ (2,853)	$ 645
Derivatives Designated as Cash Flow Hedges | Designated as hedging instruments:
Derivative Instruments, Gain (Loss) [Line Items]
Amount of (Loss) Gain Recognized in Other Comprehensive Income on Derivatives (Effective Portion)	(3,010)	599	(5,734)	(3,757)
Amount of (Loss) Gain Reclassified from Cumulative Other Comprehensive Loss into Income (Effective Portion)	$ (2,720)	$ (574)	$ (2,367)	$ 821