Equity Incentive Plans - Summary of Stock Option Activity (Details) - USD ($) $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]
Shares Subject to Options Outstanding, Beginning	5,107,329
Shares Subject to Options Outstanding, Options granted	4,194,624	5,143,551	0
Shares Subject to Options Outstanding, Option exercised	(419,593)
Shares Subject to Options Outstanding, Options forfeited/cancelled	(344,300)	(36,222)
Shares Subject to Options Outstanding, Ending	8,538,060	5,107,329
Shares Subject to Options Outstanding, Options vested and exercisable as of December 31,2019	1,215,471
Weighted-Average Exercise Price, Outstanding, beginning	$ 7.51
Weighted-Average Exercise Price, Options granted	20.11	$ 7.49
Weighted-Average Exercise Price, Option exercised	4.87
Weighted-Average Exercise Price, Options forfeited/cancelled	11.64	4.85
Weighted-Average Exercise Price, Outstanding, ending	13.67	$ 7.51
Weighted-Average Exercise Price, Options vested and exercisable as of December 31, 2019	$ 7.25
Weighted-Average Remaining Contractual Life (Years), Outstanding	9 years	9 years 8 months 12 days	0 years
Weighted-Average Remaining Contractual Life (Years), Options vested and exercisable	8 years 8 months 12 days
Aggregate Intrinsic Value, Outstanding	$ 35,385	$ 16,343
Aggregate Intrinsic Value, Options vested and exercisable	$ 10,183