Derivatives and Hedging - Derivative Contracts Not Designated as Hedging Instruments (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Foreign currency contracts
Derivatives
Total gross notional amount	$ 416,000
Embedded derivatives
Derivatives
Total gross notional amount	29,000
Embedded derivatives | Total cost of revenue
Derivatives
Net losses associated with derivative contracts	61	$ 1,000
Not designated as hedging instrument | Foreign currency contracts
Derivatives
Total gross notional amount	$ 31,000