Debt - Interest Expense of Convertible Notes (Details) - USD ($) $ in Thousands	12 Months Ended
Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Debt Instrument [Line Items]
Interest Expense	$ 26,500	$ 15,300	$ 2,500
Convertible Senior Notes Due 2024 \| Convertible debt
Debt Instrument [Line Items]
Stated interest	4,751	1,476
Amortized debt discount	20,837	5,989
Amortized issuance costs	885	254
Interest Expense	$ 26,473	$ 7,719

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

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Represents the portion of interest incurred in the period on debt arrangements that was charged against earnings, excluding amortization of debt discount (premium) and financing costs.

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