Stock Option Plan - Vested or Expected to Vest (Details) - USD ($) $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Options outstanding and exercisable
Vested, Number of Shares (in shares)	4,121,317
Vested, Weighted Average Exercise Price (in dollars per share)	$ 7.51
Vested, Weighted Average Remaining Contractual Life	5 years 11 months 12 days
Vested, Aggregate Intrinsic Value	$ 1,995
Expected to vest, Number of Shares (in shares)	2,884,933
Expected to vest, Weighted Average Exercise Price (in dollars per share)	$ 2.02
Expected to vest, Weighted Average Remaining Contractual Life	8 years 11 months 8 days
Fair value of common stock (in dollars per share)	$ 0.85
Aggregate intrinsic value of stock options exercised	$ 0	$ 1,000	$ 300
Fair value of options vested	$ 2,800	$ 4,500	$ 6,000