Quarterly report pursuant to Section 13 or 15(d)

Convertible Preferred Stock, Common Stock and Stockholders' Equity (Deficit) - Summary of Common Stock Reserved for Future Issuance (Detail)

v3.21.2
Convertible Preferred Stock, Common Stock and Stockholders' Equity (Deficit) - Summary of Common Stock Reserved for Future Issuance (Detail) - shares
Sep. 30, 2021
Dec. 31, 2020
Schedule for Common Stock Reserved for Future Issuance [Line Items]    
Total shares of authorized common stock reserved for future issuance 57,125,000 130,804,276
Common stock options outstanding and unvested RSU [Member]    
Schedule for Common Stock Reserved for Future Issuance [Line Items]    
Total shares of authorized common stock reserved for future issuance 20,411,434 18,493,013
Shares available for issuance under the 2021 plan [Member]    
Schedule for Common Stock Reserved for Future Issuance [Line Items]    
Total shares of authorized common stock reserved for future issuance 22,088,566 0
Shares available for issuance under the 2013 plan [Member]    
Schedule for Common Stock Reserved for Future Issuance [Line Items]    
Total shares of authorized common stock reserved for future issuance 0 4,427,323
Convertible preferred stock outstanding [Member]    
Schedule for Common Stock Reserved for Future Issuance [Line Items]    
Total shares of authorized common stock reserved for future issuance 0 107,592,801
Warrants to purchase Series D convertible preferred stock [Member]    
Schedule for Common Stock Reserved for Future Issuance [Line Items]    
Total shares of authorized common stock reserved for future issuance 0 110,211
Common stock warrants outstanding [Member]    
Schedule for Common Stock Reserved for Future Issuance [Line Items]    
Total shares of authorized common stock reserved for future issuance 8,525,000 180,928
Shares available for issuance as Earnout RSU [Member]    
Schedule for Common Stock Reserved for Future Issuance [Line Items]    
Total shares of authorized common stock reserved for future issuance 1,400,000 0
Employee Stock Purchase Plan [Member]    
Schedule for Common Stock Reserved for Future Issuance [Line Items]    
Total shares of authorized common stock reserved for future issuance 4,700,000 0