Derivative Financial Instruments - Schedule of Effect of Derivative Instruments on Statements of Financial Performance (Detail) (USD $) In Thousands, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2014	Jun. 30, 2013	Jun. 30, 2014	Jun. 30, 2013
Derivatives Designated As Hedges [Member] | Cash Flow Hedges [Member] | FX Forward Contracts [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Amount of gain (loss) recognized in other comprehensive income	$ 1,122	$ (2,212)	$ (192)	$ (5,210)
Derivatives Designated As Hedges [Member] | Cash Flow Hedges [Member] | FX Forward Contracts [Member] | Revenues [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Gain (loss) reclassified from accumulated other comprehensive income into earnings: effective portion	(240)	(621)	(77)	(1,152)
Derivatives Designated As Hedges [Member] | Cash Flow Hedges [Member] | FX Forward Contracts [Member] | Cost of Operations [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Gain (loss) reclassified from accumulated other comprehensive income into earnings: effective portion	1,153	(1,117)	127	(2,006)
Derivatives Designated As Hedges [Member] | Cash Flow Hedges [Member] | FX Forward Contracts [Member] | Other-net [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Gain (loss) reclassified from accumulated other comprehensive income into earnings: effective portion		101	10	116
Gain (loss) recognized in income: portion excluded from effectiveness testing	211	161	278	353
Derivatives Not Designated as Hedges [Member] | Forward Contracts [Member] | Other-net [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Gain (loss) recognized in income	$ (280)	$ 93	$ 155	$ (583)