Stockholders' Equity (Deficit) (Summary of Activity Related to Stock Options) (Details) - USD ($) $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Number of Options Outstanding
Beginning balance (in shares)	11,649,592	8,913,271
Granted (in shares)	4,217,275	3,903,750
Exercised (in shares)	(271,079)	(909,997)
Forfeited (in shares)	(519,423)	(257,432)
Ending balance (in shares)	15,076,365	11,649,592	8,913,271
Exercisable (in shares)	9,192,591
Vested and expected to vest (in shares)	14,204,938
Weighted-Average Exercise Price
Beginning balance (in dollars per share)	$ 6.27	$ 5.28
Granted (in dollars per share)	5.12	8.74
Exercised (in dollars per share)	2.24	4.69
Forfeited (in dollars per share)	6.93	15.12
Ending balance (in dollars per share)	6.00	$ 6.27	$ 5.28
Exercisable (in dollars per share)	6.14
Vested or expected to vest (in dollars per share)	$ 6.00
Additional Disclosure
Weighted-average remaining contractual life (in years)	7 years 3 months 25 days	7 years 7 months 24 days	7 years 6 months 7 days
Weighted-average remaining contractual life (in years), Exercisable	6 years 7 months 2 days
Weighted-average remaining contractual life (in years), Vested or expected to vest	7 years 3 months
Total intrinsic value of options outstanding	$ 64,174
Total intrinsic value of options exercisable	42,393
Total intrinsic value of options vested or expected to vest	$ 61,673