Stockholders' Equity - Summary of Stock Option Activity (Details) - USD ($) $ / shares in Units, $ in Thousands	9 Months Ended	12 Months Ended
	Sep. 30, 2020	Dec. 31, 2019
Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]
Options Outstanding, Beginning Balance	1,400,528
Options Outstanding, Options granted	1,134,977
Options Outstanding, Ending Balance	2,535,505	1,400,528
Options Outstanding, Options exercisable as of September 30, 2020	141,367
Weighted-Average Exercise Price, Beginning Balance	$ 9.10
Weighted-Average Exercise Price, Options granted	32.14
Weighted-Average Exercise Price, Ending Balance	19.41	$ 9.10
Weighted-Average Exercise Price, Options exercisable as of September 30, 2020	$ 12.58
Weighted-Average Remaining Contractual Term	9 years 3 months 7 days	9 years 8 months 8 days
Weighted-Average Remaining Contractual Term, Options exercisable	8 years 11 months 23 days
Aggregate Intrinsic Value, Balance	$ 43,767	$ 30,874
Aggregate Intrinsic Value, Options exercisable	$ 3,405