Income Taxes - Additional Information (Detail) - USD ($)	12 Months Ended
	Mar. 31, 2022	Mar. 31, 2021	Mar. 31, 2020	Mar. 31, 2019
Income Tax Contingency [Line Items]
Valuation allowance for company	$ 77,700,000	$ 47,500,000
U.S. Federal net operating losses	776,700,000
State net operating losses	449,300,000
U.S. Federal net operating losses, amount limited to 80% of taxable income, carried forward indefinitely	$ 355,200,000
U.S. Federal net operating losses, taxable income threshold	80.00%
U.S. Federal net operating losses, amount subject to expiration in 2028	$ 421,500,000
Minimum percentage of ownership required to increase in stock of the ownership	5.00%
Increase in ownership percentage of certain stockholders	5000.00%
Unrecognized tax benefits	$ 14,988,000	12,159,000	$ 10,338,000	$ 7,997,000
Unrecognized tax benefits that would affect income tax expense	14,800,000
Accrued interest and penalties related to uncertain tax positions	0	$ 0	$ 0
U.S. | Research and Development
Income Tax Contingency [Line Items]
Research and development credits	37,400,000
California | Research and Development
Income Tax Contingency [Line Items]
Research and development credits	6,100,000
Oregon | Research and Development
Income Tax Contingency [Line Items]
Research and development credits	$ 1,000,000