Stockholders' Equity - Schedule of Common Stock Reserved for Issuance (Detail) - shares	6 Months Ended	12 Months Ended
	Sep. 30, 2023	Mar. 31, 2023
Class Of Stock [Line Items]
Outstanding stock options	75,637,943	68,050,752
Total shares of common stock reserved	221,253,765	163,884,802
2021 Incentive Equity Plan
Class Of Stock [Line Items]
Remaining shares available for future issuance under 2021 Incentive Equity Plan	93,024,795	55,922,182
Employee Stock Purchase Plan
Class Of Stock [Line Items]
Remaining shares available for future issuance under Employee Stock Purchase Plan	11,839,766	13,349,302
Restricted Stock Units
Class Of Stock [Line Items]
Outstanding restricted stock units	40,751,261	26,562,566