Fair Value Measurements - Gains and Losses on Derivative Instruments in Consolidated Statements of Income (Detail) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Not designated as hedging instruments: | Other non-operating expense | Foreign Exchange Contracts
Derivative Instruments, Gain (Loss) [Line Items]
Amount of (Loss) Gain Recognized in Income on Derivatives	$ 2,324	$ (759)	$ 43	$ (1,405)
Derivatives Designated as Cash Flow Hedges | Designated as hedging instruments:
Derivative Instruments, Gain (Loss) [Line Items]
Amount of Gain (Loss) Recognized in Other Comprehensive Income on Derivatives (Effective Portion)	2,062	(2,335)	2,708	(2,724)
Amount of Gain Reclassified from Cumulative Other Comprehensive Loss into Income (Effective Portion)	$ 1,592	$ 343	$ 98	$ 353