Debt Facilities - Schedule of Interest Expense (Details) - 2019 Convertible Senior Notes due 2026 - USD ($) $ in Thousands	3 Months Ended	6 Months Ended
Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020
Debt Instrument [Line Items]
Amortization of debt discount		$ 886		$ 1,740
Amortization of debt issuance costs	$ 93	27	$ 187	53
Cash interest expense	432	436	863	868
Total interest expense	$ 525	$ 1,349	$ 1,050	$ 2,661

Cash interest expense.

No definition available.

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Amount of noncash expense included in interest expense to amortize debt discount and premium associated with the related debt instruments. Excludes amortization of financing costs. Alternate captions include noncash interest expense.

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Amount of amortization expense attributable to debt issuance costs.

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Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

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- Definition

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

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