Stock-Based Compensation - Summary of Stock Option Activity (Details) - USD ($) $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Stock-Based Compensation
Options Available for Grant, Outstanding, Beginning balance	342,500	55,330
Options Available for Grant, Options authorized	374,944	785,364
Options Available for Grant, RSUs granted	(30,680)
Options Available for Grant, Options granted	(757,900)	(563,523)
Options Available for Grant, Options cancelled/forfeited	155,065	65,329
Options Available for Grant, Outstanding, Ending balance	83,929	342,500	55,330
Number of Options, Outstanding, Beginning balance	1,414,730	927,175
Number of Options, Options granted	757,900	563,523
Number of Options, Options exercised	(281,483)	(10,639)
Number of Options, Options cancelled/forfeited	(297,952)	(65,329)
Number of Options, Outstanding, Ending balance	1,593,195	1,414,730	927,175
Number of Options, exercisable	766,233
Number of Options, vested and expected to vest	1,593,195
Weighted - Average Exercise Price Per Share, Options outstanding, Beginning balance	$ 5.28	$ 4.43
Weighted - Average Exercise Price Per Share, Options granted	13.02	13.20
Weighted - Average Exercise Price Per Share, Options exercised	4.75	4.43
Weighted - Average Exercise Price Per Share, Options cancelled/forfeited	6.13	4.71
Weighted - Average Exercise Price Per Share, Options outstanding, Ending balance	8.88	$ 5.28	$ 4.43
Weighted - Average Exercise Price Per Share, Options exercisable	5.43
Weighted - Average Exercise Price Per Share, Options vested and expected to vest	$ 8.88
Weighted - Average Remaining Contractual Life, Options outstanding	6 years 7 months 6 days	7 years 7 months 6 days	7 years 3 months 18 days
Weighted - Average Remaining Contractual Life, Options exercisable	3 years 8 months 12 days
Weighted - Average Remaining Contractual Life, Options vested and expected to vest	6 years 7 months 6 days
Aggregate Intrinsic Value, Options outstanding	$ 1,997	$ 4,267	$ 6,500
Aggregate Intrinsic Value, Options exercised	2,101	$ 114
Aggregate Intrinsic Value, Options exercisable	1,825
Aggregate Intrinsic Value, Options vested and expected to vest	$ 1,997