0.5% Convertible Senior Notes and Capped Call - Schedule of Interest Expense (Details) - USD ($) $ in Thousands	3 Months Ended	9 Months Ended
Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2019	Dec. 31, 2018
Debt Instrument [Line Items]
Total interest expense	$ 5,939	$ 5,646	$ 17,594	$ 13,861
Convertible Debt \| Convertible Senior Notes Due 2023
Debt Instrument [Line Items]
Amortization of debt discount	4,901	4,654	14,515	11,421
Amortization of issuance costs	413	367	1,203	891
Contractual interest expense	$ 625	$ 625	$ 1,876	$ 1,549

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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