Derivatives and Hedge Accounting - Summary of Effect of Foreign Currency Exchange Contracts on Consolidated Statements of Income (Details) - Foreign Currency Exchange Contracts - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2017	Jun. 30, 2016
Derivatives Designated as Hedging Instruments | Derivatives in Cash Flow Hedging Relationships
Derivative Instruments, Gain (Loss) [Line Items]
Gain/(loss) recognized in AOCL on derivative - Effective portion	$ 770	$ (1,884)	$ 9,493	$ 553
Foreign exchange gain/(loss) | Derivatives Designated as Hedging Instruments | Derivatives in Cash Flow Hedging Relationships
Derivative Instruments, Gain (Loss) [Line Items]
Gain/(loss) reclassified from AOCL to foreign exchange gain/(loss) - Effective portion	510	349	1,134	406
Gain/(loss) recognized in foreign exchange gain/(loss) - Ineffective portion	0	0	0	0
Foreign exchange gain/(loss) | Derivatives not Designated as Hedging Instruments
Derivative Instruments, Gain (Loss) [Line Items]
Gain/(loss) recognized in foreign exchange gain/(loss)	$ 151	$ 999	$ 2,773	$ 2,728