Accrued Expenses (Details) - USD ($) $ in Thousands	Jun. 30, 2020	Mar. 31, 2020
Payables and Accruals [Abstract]
Accrued R&D expenses	$ 15,437	$ 15,500
Accrued compensation-related expenses	6,994	9,309
Accrued commercial expenses	3,190	818
Accrued professional service fees	763	1,126
Accrued other expenses	2,536	2,307
Total accrued expenses	$ 28,920	$ 29,060