Hedging - Notional Amount (Details) - Cash Flow Hedging - Foreign currency forward contracts - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015
Designated as Hedging Instrument
Derivative [Line Items]
Notional amount of foreign currency forward contract	$ 253,381	$ 209,285
Designated as Hedging Instrument | Euro
Derivative [Line Items]
Notional amount of foreign currency forward contract	164,368	103,362
Designated as Hedging Instrument | British pound sterling
Derivative [Line Items]
Notional amount of foreign currency forward contract	65,237	78,756
Designated as Hedging Instrument | Australian dollar
Derivative [Line Items]
Notional amount of foreign currency forward contract	$ 23,776	$ 27,167
Minimum
Derivative [Line Items]
Derivative term	1 month
Maximum
Derivative [Line Items]
Derivative term	18 months