Stock-Based Compensation - Summary of Employee and Non-Employee Stock Option Activity (Details) - USD ($) $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017
Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]
Shares Issuable Under Options, Outstanding	2,361,360
Shares Issuable Under Options, Granted	1,668,800
Shares Issuable Under Options, Exercised	(521,665)
Shares Issuable Under Options, Forfeited	(365,808)
Shares Issuable Under Options, Outstanding	3,142,687	2,361,360
Shares Issuable Under Options, Options vested and expected to vest	2,939,785
Shares Issuable Under Options, Options exercisable	1,160,819
Weighted Average Exercise Price, Outstanding	$ 5.21
Weighted Average Exercise Price, Granted	8.03
Weighted Average Exercise Price, Exercised	5.42
Weighted Average Exercise Price, Forfeited	5.20
Weighted Average Exercise Price, Outstanding	6.67	$ 5.21
Weighted Average Exercise Price, Options vested and expected to vest	6.49
Weighted Average Exercise Price, Options exercisable	$ 5.85
Weighted Average Remaining Contractual Term, Outstanding	8 years 6 months 7 days	8 years 8 months 19 days
Weighted Average Remaining Contractual Term, Options vested and expected to vest	8 years 5 months 12 days
Weighted Average Remaining Contractual Term, Options exercisable	7 years 8 months 4 days
Aggregate Intrinsic Value, Outstanding	$ 4,798	$ 2,482
Aggregate Intrinsic Value, Options vested and expected to vest	4,786
Aggregate Intrinsic Value, Options exercisable	$ 2,470