Common Stock - Summary of Common Stock Capital Shares Reserved For Future Issuance (Detail) - shares |
Mar. 31, 2021 |
Mar. 31, 2020 |
Mar. 31, 2019 |
|---|---|---|---|
| Common Stock Capital Shares Reserved For Future Issuance [Line Items] | |||
| Shares of common stock reserved | 121,596,812 | 120,215,617 | 122,610,399 |
| Conversion of redeemable convertible preferred stock | |||
| Common Stock Capital Shares Reserved For Future Issuance [Line Items] | |||
| Shares of common stock reserved | 91,198,378 | 86,443,341 | 86,443,341 |
| Outstanding stock options | |||
| Common Stock Capital Shares Reserved For Future Issuance [Line Items] | |||
| Shares of common stock reserved | 29,375,026 | 29,817,566 | 28,067,150 |
| Equity Incentive Plan [Member] | Remaining shares available for future issuance under Equity Incentive Plan | |||
| Common Stock Capital Shares Reserved For Future Issuance [Line Items] | |||
| Shares of common stock reserved | 1,023,408 | 3,954,710 | 8,099,908 |