Certain Balance Sheet Components - Accrued Expenses and Other Current Liabilities (Details) - USD ($) $ in Thousands	Sep. 30, 2022	Mar. 31, 2022
Other Liabilities Disclosure [Abstract]
Accrued sales discounts, rebates, and allowances	$ 38,620	$ 19,390
Accrued compensation-related expenses	18,171	26,389
Accrued R&D expenses	7,081	6,955
Accrued commercial expenses	6,387	7,196
Accrued royalties payable to Takeda	3,769	2,470
Accrued professional fees	3,595	1,340
Accrued income tax payable	2,977	720
Accrued other expenses	2,864	3,309
Deferred product revenue	617	825
Total accrued expenses and other current liabilities	$ 84,081	$ 68,594