Stockholders' Deficit - Additional Information (Details) - USD ($)	3 Months Ended		9 Months Ended		12 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020	Dec. 31, 2020	Oct. 21, 2021
Subsidiary or Equity Method Investee [Line Items]
Common stock, shares authorized	144,406,928		144,406,928		144,406,928
Aggregate intrinsic value of common stock exercised	$ 700,000	$ 0	$ 1,500,000	$ 0
Fair value of options vested			$ 5,100,000	$ 500,000
Weighted average grant date fair value			$ 7.07	$ 0.36
Unrecognized stock-based compensation expense	$ 10,000,000.0		$ 10,000,000.0
Compensation expense not yet recognized, period for recognition			2 years 9 months 3 days
Repurchase of common stock			0	0
Shares subject to repurchase			410,788	0	136,032
Aggregate exercise prices of early exercised shares			$ 300,000		$ 100,000
Common stock, par value	$ 0.001		$ 0.001		$ 0.001
Incremental compensation cost				$ 300,000
Subsequent Event
Subsidiary or Equity Method Investee [Line Items]
Common stock, shares authorized						100,000,000
Common stock, par value						$ 0.001
Preferred stock, shares authorized						5,000,000
Preferred stock, par value						$ 0.001
Maximum [Member]
Subsidiary or Equity Method Investee [Line Items]
Incremental compensation cost			$ 100,000