Stock-Based Compensation - Summary of Stock Option Activity (Details) - 2002 Plan and 2018 Plan - USD ($)	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Stock Option Activity Under the 2002 Plan and 2018 Plan
Outstanding (in shares)	1,545,403	1,075,209
Granted (in shares)	1,260,540	563,268
Exercised (in shares)	(143,654)	(43,687)
Cancelled or expired (in shares)	(84,571)	(49,387)
Outstanding (in shares)	2,577,718	1,545,403	1,075,209
Vested and expected to vest (in shares)	2,577,718
Stock Options Weighted Average Exercise Price
Outstanding (in usd per share)	$ 2.48	$ 1.60
Granted (in usd per share)	4.19	4.07
Exercised (in usd per share)	1.71	2.12
Cancelled or expired (in usd per share)	4.65	1.65
Outstanding (in usd per share)	3.29	$ 2.48	$ 1.60
Vested and expected to vest (in usd per share)	$ 3.29
Stock Option Activity, Additional Disclosures
Weighted- average remaining contractual term, outstanding	7 years 11 months 1 day	7 years 7 months 6 days	7 years 3 months 18 days
Weighted-average remaining contractual term, vested and expected to vest	7 years 11 months 1 day
Aggregate intrinsic value, outstanding	$ 7,914,459	$ 1,593,487	$ 711,328
Aggregate intrinsic value, vested and expected to vest	$ 7,914,459
Total options, vested and exercisable	1,157,120
Weighted-average exercise price per share, vested and exercisable	$ 2.25
Weighted-average remaining contractual term, vested and exercisable	6 years 8 months 26 days
Aggregate intrinsic value, vested and exercisable	$ 4,469,348