Convertible Senior Notes - Expenses and Interest (Details) - USD ($) $ in Thousands	6 Months Ended
Jun. 30, 2021	Jun. 30, 2020
Debt Instrument [Line Items]
Amortization of debt issuance costs and discount on convertible senior notes	$ 1,726	$ 6,528
3.75% Convertible Senior Notes
Debt Instrument [Line Items]
Interest expense	1,850
Amortization of debt issuance costs and discount on convertible senior notes	306
Total	$ 2,156
Effective interest rate (as a percent)	4.50%

Amount of amortization expense attributable to 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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Interest and debt related expenses associated with nonoperating financing activities of the entity.

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Amount of the cost of borrowed funds accounted for as interest expense for debt.

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