Certain Balance Sheet Components - Accrued Expenses and Other Current Liabilities (Details) - USD ($) $ in Thousands	Sep. 30, 2021	Mar. 31, 2021
Other Liabilities Disclosure [Abstract]
Accrued compensation-related expenses	$ 17,111	$ 20,571
Accrued sales discounts, rebates, and allowances	10,493	1,315
Accrued R&D expenses	7,354	8,544
Accrued commercial expenses	7,226	7,770
Accrued other expenses	3,525	5,315
Accrued professional fees	625	935
Deferred product revenue	0	162
Total accrued expenses and other current liabilities	$ 46,334	$ 44,612