Share-based Compensation - Summary of Stock Option Activity (Detail) - USD ($) $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018
Stock Options Outstanding
Outstanding — beginning of period	8,796,212
Granted	2,660,936
Exercised	(1,489,067)	(1,611,731)
Canceled	(923,777)
Outstanding — end of period	9,044,304	8,796,212
Vested and Expected to Vest — December 31, 2019	7,814,925
Exercisable — December 31, 2019	3,648,992
Weighted-Average Exercise Price Per Option
Outstanding — beginning of period	$ 2.10
Granted	5.17
Exercised	1.69
Canceled	3.64
Outstanding — end of period	2.91	$ 2.10
Vested and Expected to Vest — December 31, 2019	2.75
Exercisable — December 31, 2019	$ 1.93
Weighted-Average Remaining Contractual Term (Years), Options Outstanding	8 years 3 months 18 days
Weighted-Average Remaining Contractual Term (Years), Options Vested and Expected to Vest	8 years 2 months 1 day
Weighted-Average Remaining Contractual Term (Years), Options Exercisable	7 years 3 months 10 days
Aggregate Intrinsic Value, Options Outstanding	$ 39,997
Aggregate Intrinsic Value, Options Vested and Expected to Vest	35,753
Aggregate Intrinsic Value, Options Exercisable	$ 19,735