Share-Based Compensation - Stock Option Activity (Details) - Stock Options - USD ($) $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Number of Options
Outstanding at beginning of period (in shares)	6,028,000	4,146,000
Granted (in shares)	150,000	2,015,000
Forfeited and Expired (in shares)	(444,000)	(133,000)
Exercised (in shares)	(1,000)
Outstanding at end of period (in shares)	5,733,000	6,028,000	4,146,000
Vested or expected to vest (in shares)	5,674,000
Exercisable at end of period (in shares)	4,324,000
Weighted Average Exercise Price
Outstanding at beginning of period (in dollars per share)	$ 5.48	$ 7.28
Granted (in dollars per share)	2.02	1.83
Forfeited and Expired (in dollars per share)	2.27	7.81
Exercised (in dollars per share)	0.88
Outstanding at end of period (in dollars per share)	5.58	$ 5.48	$ 7.28
Vested or expected to vest at end of period (in dollars per share)	5.62
Exercisable at end of period (in dollars per share)	$ 6.59
Weighted Average Remaining Contractual Term in Years
Weighted average remaining contractual term	6 years 4 months 28 days	7 years 6 months	7 years 10 months 17 days
Weighted average remaining contractual term, vested or expected to vest	6 years 3 months 25 days
Weighted average remaining contractual term, exercisable	5 years 11 months 23 days
Aggregate Intrinsic Value
Intrinsic value	$ 1,082	$ 38	$ 1,423
Intrinsic value, vested or expected to vest at end of period	1,050
Intrinsic value, exercisable at end of period	$ 596