Unsecured Convertible Senior Notes - Future minimum payments (Details) - USD ($) $ in Thousands	Jun. 30, 2021	Dec. 31, 2020
Long-term Debt, Fiscal Year Maturity [Abstract]
Total future minimum payments under the convertible senior notes	$ 320,030	$ 320,030
2023 and 2026 Convertible Senior Notes
Long-term Debt, Fiscal Year Maturity [Abstract]
2023	95,000
2026	225,030
Total future minimum payments under the convertible senior notes	$ 320,030

Amount, before unamortized (discount) premium and debt issuance costs, of long-term debt. Includes, but is not limited to, notes payable, bonds payable, commercial loans, mortgage loans, convertible debt, subordinated debt and other types of debt.

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Amount of long-term debt payable, sinking fund requirement, and other securities issued that are redeemable by holder at fixed or determinable price and date, maturing in fifth fiscal year following current fiscal year. Excludes interim and annual periods when interim periods are reported from current statement of financial position date (rolling approach).

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Amount of long-term debt payable, sinking fund requirement, and other securities issued that are redeemable by holder at fixed or determinable price and date, maturing in second fiscal year following current fiscal year. Excludes interim and annual periods when interim periods are reported from current statement of financial position date (rolling approach).

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