Derivatives and Hedging Activities - Derivatives Not Designated as Hedging Instruments (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Derivatives not designated as hedging instruments, gain (loss)	$ 77,253	$ 17,381	$ 97,015	$ 61,583
Embedded derivatives [Member] | Revenues [Member]
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Derivatives not designated as hedging instruments, gain (loss)	2,830	742	3,552	2,206
Economic hedge of embedded derivatives [Member] | Revenues [Member]
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Derivatives not designated as hedging instruments, gain (loss)	(3,221)	(422)	(2,680)	(1,360)
Foreign currency forward contract [Member] | Other income (expense) [Member]
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Derivatives not designated as hedging instruments, gain (loss)	$ 77,644	$ 17,061	$ 96,143	$ 60,737