Equity Incentive Plan - Stock option (Details) - 2019 Plan and Company's 2010 Plan - USD ($) $ / shares in Units, $ in Thousands	6 Months Ended	12 Months Ended
	Jun. 30, 2022	Dec. 31, 2021
Number of Shares
Balance at beginning of period (in shares)	7,162,676
Granted (in shares)	404,700
Exercised (in shares)	(16,666)
Cancelled (in shares)	(422,345)
Balance at end of period (in shares)	7,128,365	7,162,676
Vested and expected to vest at end of period (in shares)	7,128,365
Exercisable at end of period (in shares)	3,984,931
Vested at end of period (in shares)	3,984,931
Weighted-Average Exercise Price
Balance at beginning of period (in dollars per share)	$ 11.25
Granted (in dollars per share)	1.93
Exercised (in dollars per share)	4.56
Cancelled (in dollars per share)	10.95
Balance at end of period (in dollars per share)	3.87	$ 11.25
Vested and expected to vest at end of period (in dollars per share)	3.87
Exercisable at end of period (in dollars per share)	4.58
Vested at end of period (in dollars per share)	$ 4.58
Weighted-Average Remaining Contractual Life
Weighted-average remaining contractual life of options (years)	7 years 9 months 18 days	8 years 2 months 12 days
Vested and expected to vest at end of period (in years)	7 years 9 months 18 days
Exercisable at end of period (in years)	7 years
Vested at end of period (in years)	7 years
Aggregate Intrinsic Value
Aggregate intrinsic value of options	$ 19	$ 21
Vested and expected to vest at end of period	19
Exercisable at end of period	10
Vested at end of period	$ 10