Stockholders' Equity - Summary of Stock Option Activity (Details) - USD ($) $ / shares in Units, $ in Thousands	9 Months Ended	12 Months Ended
	Sep. 30, 2021	Dec. 31, 2020
Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]
Options Outstanding, Beginning Balance	2,728,742
Options Outstanding, Options granted	1,568,250
Options Outstanding, Options exercised and shares vested	(95,071)
Options Outstanding, Options cancelled	(107,605)
Options Outstanding, Ending Balance	4,094,316	2,728,742
Options Outstanding, Options exercisable as of June 30, 2021	941,254
Weighted-Average Exercise Price, Beginning Balance	$ 21.36
Weighted-Average Exercise Price, Options granted	38.61
Weighted-Average Exercise Price, Options exercised and shares vested	18.73
Weighted-Average Exercise Price, Options cancelled	34.07
Weighted-Average Exercise Price, Ending Balance	27.70	$ 21.36
Weighted-Average Exercise Price, Options exercisable as of June 30,2021	$ 18.73
Weighted-Average Remaining Contractual Term	8 years 7 months 24 days	9 years 1 month 6 days
Weighted-Average Remaining Contractual Term, Options exercisable	7 years 11 months 12 days
Aggregate Intrinsic Value, Balance	$ 30,591	$ 34,432
Aggregate Intrinsic Value, Options exercisable	$ 13,122