Stock-Based Compensation - Summary of Stock Option Activity (Details) - USD ($)	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020
Number of Shares
Outstanding, beginning (in shares)	7,656,623	6,439,936
Granted (in shares)	2,397,684	2,032,000
Exercised (in shares)	(1,250)	(3,542)
Forfeited (in shares)	(34,565)	(170,187)
Expired (in shares)	(513,031)	(641,584)
Outstanding, ending (in shares)	9,505,461	7,656,623
Vested (exercisable) (in shares)	6,371,266
Unvested (unexercisable) (in shares)	3,134,195
Weighted- Average Exercise Price/Share
Outstanding, beginning (in dollars per share)	$ 7.80	$ 9.61
Granted (in dollars per share)	2.66	2.34
Exercised (in dollars per share)	3.04	3.70
Forfeited (in dollars per share)	10.05	8.29
Expired (in dollars per share)	9.29	8.55
Outstanding, ending (in dollars per share)	6.42	$ 7.80
Vested (exercisable) (in dollars per share)	8.04
Unvested (unexercisable) (in dollars per share)	$ 3.13
Weighted-Average Remaining Contractual Term (in years), outstanding	5 years 10 months 9 days
Weighted-Average Remaining Contractual Term (in years), vested (exercisable)	4 years 3 months 3 days
Weighted-Average Remaining Contractual Term (in years), unvested (unexercisable)	9 years 1 month 6 days
Exercised, Aggregate Intrinsic Value	$ 1,500	$ 708,000
Aggregate Intrinsic Value, outstanding (exercisable)	0
Aggregate Intrinsic Value, vested (exercisable)	0
Aggregate Intrinsic Value, unvested (unexercisable)	$ 0