Stock-based Compensation, Stock Options (Details) - Stock Options [Member] - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended		12 Months Ended
	Mar. 31, 2024	Mar. 31, 2023	Dec. 31, 2023
Stock Options [Abstract]
Stock-based compensation	$ 1,300	$ 2,300
Number of Options [Roll Forward]
Outstanding, beginning balance (in shares)	22,511,900
Granted (in shares)	0
Exercised (in shares)	0
Forfeited (in shares)	(384,573)
Expiration (in shares)	(25,520)
Outstanding, ending balance (in shares)	22,101,807		22,511,900
Exercisable (in shares)	7,918,930
Vested and expected to vest (in shares)	18,615,698
Weighted Average Exercise Price [Roll Forward]
Outstanding, beginning balance (in dollars per share)	$ 2.79
Granted (in dollars per share)	0
Exercised (in dollars per share)	0
Forfeited (in dollars per share)	3.78
Expiration (in dollars per share)	0.06
Outstanding, ending balance (in dollars per share)	2.78		$ 2.79
Exercisable (in dollars per share)	3.52
Vested and expected to vest (in dollars per share)	$ 2.85
Weighted Average Remaining Contractual Term and Aggregate Intrinsic Value [Abstract]
Weighted average remaining contractual term, outstanding	8 years 3 days		8 years 2 months 19 days
Weighted average remaining contractual term, exercisable	6 years 7 months 24 days
Weighted average remaining contractual term, vested and expected to vest	7 years 10 months 9 days
Aggregate intrinsic value, outstanding, beginning balance	$ 3,194
Aggregate intrinsic value, outstanding, ending balance	2,832		$ 3,194
Aggregate intrinsic value, exercisable	610
Aggregate intrinsic value, vested and expected to vest	$ 2,286