Equity Incentive Plans - Summary of Stock Option Activity Under 2009 Plan and 2019 Plan (Details) $ / shares in Units, $ in Thousands	3 Months Ended
	Mar. 31, 2022 USD ($) $ / shares shares
Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]
Shares Subject to Outstanding Stock Options, Stock Options outstanding, Beginning Balance | shares	12,778,984
Shares Subject to Outstanding Stock Options, Stock Options granted | shares	3,730,851
Shares Subject to Outstanding Stock Options, Stock Options forfeited or cancelled | shares	(795,626)
Shares Subject to Outstanding Stock Options, Stock Options expired | shares	(50,073)
Shares Subject to Outstanding Stock Options, Stock Options exercised | shares	(648,208)
Shares Subject to Outstanding Stock Options, Stock Options outstanding, Ending Balance | shares	15,015,928
Shares Subject to Outstanding Stock Options, Stock Options vested and exercisable | shares	7,387,511
Weighted Average Exercise Price per Share, Stock Options outstanding, Beginning Balance | $ / shares	$ 19.72
Weighted Average Exercise Price per Share, Stock Options granted | $ / shares	12.43
Weighted Average Exercise Price per Share, Stock Options forfeited or cancelled | $ / shares	29.00
Weighted Average Exercise Price per Share, Stock Options expired | $ / shares	34.73
Weighted Average Exercise Price per Share, Stock Options exercised | $ / shares	4.22
Weighted Average Exercise Price per Share, Stock Options outstanding, Ending Balance | $ / shares	18.03
Weighted Average Exercise Price per Share, Stock Options vested and exercisable | $ / shares	$ 13.42
Aggregate Intrinsic Value, Stock Option outstanding | $	$ 51,641
Aggregate Intrinsic Value, Stock Options vested and exercisable | $	$ 42,129