Convertible Notes (Details 2) - USD ($) $ in Thousands	3 Months Ended	6 Months Ended
Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019
Interest expense related to notes
Amortization of discount and debt issuance costs			$ 3,571	$ 3,379
Interest expense	$ 2,580	$ 2,534	5,135	4,805
Convertible senior notes \| 1.375% Convertible senior notes due 2023
Interest expense related to notes
Interest	593	593	1,186	1,186
Amortization of discount and debt issuance costs	1,798	1,701	3,571	3,379
Interest expense	$ 2,391	$ 2,294	$ 4,757	$ 4,565
Convertible notes, stated interest rate (as a percentage)	1.375%	1.375%	1.375%	1.375%
Effective interest rate of the liability component (as a percentage)	4.90%	4.90%	4.90%	4.90%

Amount of amortization expense attributable to debt discount (premium) and debt issuance costs.

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Effective interest rate for the funds borrowed under the debt agreement considering interest compounding and original issue discount or premium.

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