0.5% Convertible Senior Notes and Capped Call - Schedule of Interest Expense (Details) - Convertible Debt - Convertible Senior Notes Due 2023 - USD ($) $ in Thousands	3 Months Ended
Jun. 30, 2019	Jun. 30, 2018
Debt Instrument [Line Items]
Amortization of debt discount	$ 4,776	$ 2,174
Amortization of issuance costs	389	167
Contractual interest expense	625	299
Total interest expense	$ 5,790	$ 2,640

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

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