Balance Sheet Components - Property and Equipment, Net (Details) - USD ($) $ in Thousands	Sep. 30, 2023	Mar. 31, 2023
Property Plant And Equipment [Line Items]
Property and equipment, gross	$ 113,567	$ 113,924
Less: accumulated depreciation and amortization	(80,762)	(75,316)
Property and equipment, net	32,805	38,608
Computer and Software
Property Plant And Equipment [Line Items]
Property and equipment, gross	9,993	10,376
Laboratory Equipment and Software
Property Plant And Equipment [Line Items]
Property and equipment, gross	52,803	52,785
Furniture and Office Equipment
Property Plant And Equipment [Line Items]
Property and equipment, gross	8,963	8,946
Leasehold Improvements
Property Plant And Equipment [Line Items]
Property and equipment, gross	40,955	40,964
Capitalized Asset Retirement Obligations
Property Plant And Equipment [Line Items]
Property and equipment, gross	$ 853	$ 853