Convertible Senior Notes - Summary of Interest Expense (Details) - USD ($) $ in Thousands	3 Months Ended	6 Months Ended
Jun. 30, 2020	Jun. 30, 2020
Debt Disclosure [Abstract]
Contractual interest expense	$ 970	$ 1,940
Amortization of debt discount	1,967	3,920
Amortization of issuance costs	246	490
Total interest expense	$ 3,183	$ 6,350

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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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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