0.5% Convertible Senior Notes and Capped Call - Schedule of Interest Expense (Details) - USD ($) $ in Thousands	3 Months Ended	6 Months Ended
Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Debt Instrument [Line Items]
Total interest expense	$ 6,170	$ 5,865	$ 12,261	$ 11,655
Convertible Debt \| Convertible Senior Notes Due 2023
Debt Instrument [Line Items]
Amortization of debt discount	5,095	4,838	885	790
Amortization of issuance costs	449	401	1,251	1,251
Contractual interest expense	$ 626	$ 626	$ 10,125	$ 9,614

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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