Stock-Based Compensation - 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]
Number of Options Outstanding, Beginning Balance	44,960
Number of Options, Granted	3,616,945
Number of Options Outstanding, Ending Balance	3,661,905	44,960
Options vested and exercisable at September 30, 2020	14,048
Weighted Average Exercise Price, Options outstanding as of January 1, 2020	$ 3.01
Weighted Average Exercise Price, Granted	16.89
Weighted Average Exercise Price, Options outstanding as of September 30, 2020	16.72	$ 3.01
Weighted Average Exercise Price, Options vested and exercisable at September 30, 2020	$ 3.01
Weighted Average Contractual Life, Options outstanding	9 years 9 months 18 days	9 years 6 months
Weighted Average Contractual Life, Options vested and exercisable at September 30, 2020	9 years
Aggregate Intrinsic Value, Options outstanding as of September 30, 2020	$ 39,553
Aggregate Intrinsic Value, Options vested and exercisable at September 30, 2020	$ 344