Derivative Financial Instruments - Schedule of Effect of Derivative Instruments on Statements of Financial Performance (Detail) - FX Forward Contracts - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2017	Jun. 30, 2016	Dec. 31, 2016
Designated as Hedging Instrument | Cash Flow Hedging
Derivative Instruments, Gain (Loss) [Line Items]
Amount of gain (loss) recognized in other comprehensive income	$ (3,657)	$ 847	$ 2,244	$ 4,057
Designated as Hedging Instrument | Cash Flow Hedging | Revenues
Derivative Instruments, Gain (Loss) [Line Items]
Effective portion of gain (loss) reclassified from accumulated other comprehensive income into earnings	714	1,261	6,002	2,584
Designated as Hedging Instrument | Cash Flow Hedging | Cost of operations
Derivative Instruments, Gain (Loss) [Line Items]
Effective portion of gain (loss) reclassified from accumulated other comprehensive income into earnings	(49)	10	(46)	33
Designated as Hedging Instrument | Cash Flow Hedging | Other-net
Derivative Instruments, Gain (Loss) [Line Items]
Effective portion of gain (loss) reclassified from accumulated other comprehensive income into earnings	885	(578)	492	(620)
Portion of gain (loss) recognized in income that is excluded from effectiveness testing	(113)	1,219	(3,519)	2
Derivatives Not Designated as Hedges | Other-net
Derivative Instruments, Gain (Loss) [Line Items]
Gain (loss) recognized in income	(36)	$ (303)	(345)	$ (413)
Other Accounts Receivable [Member] | Designated as Hedging Instrument
Derivative Instruments, Gain (Loss) [Line Items]
Derivative Asset	2,992		2,992		$ 3,805
Other Accounts Receivable [Member] | Derivatives Not Designated as Hedges
Derivative Instruments, Gain (Loss) [Line Items]
Derivative Asset	28		28		105
Other Assets [Member] | Designated as Hedging Instrument
Derivative Instruments, Gain (Loss) [Line Items]
Derivative Asset	69		69		665
Other Assets [Member] | Derivatives Not Designated as Hedges
Derivative Instruments, Gain (Loss) [Line Items]
Derivative Asset	7		7		0
Other Liabilities [Member] | Designated as Hedging Instrument
Derivative Instruments, Gain (Loss) [Line Items]
Derivative Liability	60		60		213
Accounts Payable [Member] | Designated as Hedging Instrument
Derivative Instruments, Gain (Loss) [Line Items]
Derivative Liability	5,214		5,214		1,012
Accounts Payable [Member] | Derivatives Not Designated as Hedges
Derivative Instruments, Gain (Loss) [Line Items]
Derivative Liability	71		71		403
Other Liabilities [Member] | Derivatives Not Designated as Hedges
Derivative Instruments, Gain (Loss) [Line Items]
Derivative Liability	$ 0		$ 0		$ 7