Stock-based Compensation, Stock Option Activity (Details) - USD ($) $ / shares in Units, $ in Thousands		12 Months Ended
	Aug. 31, 2023	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Weighted Average Remaining Contractual Term and Aggregate Intrinsic Value [Abstract]
Proceeds from exercise of stock options		$ 357	$ 2,757	$ 5,618
Chief Executive Officer [Member]
Number of Options [Roll Forward]
Granted (in shares)			6,950,000
Chief Financial Officer [Member]
Number of Options [Roll Forward]
Granted (in shares)		2,000,000
President and Chief Operating Officer [Member]
Number of Options [Roll Forward]
Granted (in shares)			2,000,000
Forfeited (in shares)	(1,708,334)
2021 Plan [Member] | Chief Executive Officer [Member]
Number of Options [Roll Forward]
Granted (in shares)			4,170,000
2021 Plan [Member] | Chief Financial Officer [Member]
Number of Options [Roll Forward]
Granted (in shares)		1,000,000
2023 Inducement Plan [Member] | Chief Executive Officer [Member]
Number of Options [Roll Forward]
Granted (in shares)			2,780,000
2023 Inducement Plan [Member] | Chief Financial Officer [Member]
Number of Options [Roll Forward]
Granted (in shares)		1,000,000
Stock Options [Member]
Stock Option Activity [Abstract]
Stock-based compensation expense		$ 7,100	$ 7,300	$ 6,100
Number of Options [Roll Forward]
Outstanding, beginning balance (in shares)		19,427,755	7,726,972	7,369,541
Granted (in shares)		10,138,730	14,271,330	3,514,510
Exercised (in shares)		(140,559)	(1,123,249)	(2,661,252)
Forfeited (in shares)		(6,914,026)	(1,447,298)	(495,827)
Outstanding, ending balance (in shares)		22,511,900	19,427,755	7,726,972	7,369,541
Exercisable (in shares)		6,799,386
Vested and expected to vest (in shares)		18,629,173
Weighted Average Exercise Price [Roll Forward]
Outstanding, beginning balance (in dollars per share)		$ 3.69	$ 5.14	$ 2.37
Granted (in dollars per share)		1.79	3.04	8.89
Exercised (in dollars per share)		2.55	2.45	2.11
Forfeited (in dollars per share)		3.86	5.43	6.84
Outstanding, ending balance (in dollars per share)		2.79	$ 3.69	$ 5.14	$ 2.37
Options exercisable (in dollars per share)		3.73
Vested and expected to vest (in dollars per share)		$ 2.87
Weighted Average Remaining Contractual Term and Aggregate Intrinsic Value [Abstract]
Weighted average remaining contractual term, outstanding		8 years 2 months 19 days	8 years 8 months 4 days	7 years 6 months 29 days	6 years 9 months 7 days
Weighted average remaining contractual term, options exercisable		6 years 5 months 12 days
Weighted average remaining contractual term, vested and expected to vest		8 years 21 days
Aggregate intrinsic value, outstanding, beginning balance		$ 378	$ 24,511	$ 4,094
Aggregate intrinsic value, outstanding, ending balance		3,194	378	24,511	$ 4,094
Aggregate intrinsic value, options exercisable		406
Aggregate intrinsic value, vested and expected to vest		2,505
Proceeds from exercise of stock options		400	2,800	5,600
Intrinsic value of stock options exercised		100	$ 1,900	17,200
Stock Options Subject to Performance Condition Related to Business Combination [Member]
Stock Option Activity [Abstract]
Stock-based compensation expense		$ 0		$ 3,100
Stock Options Subject to Performance Condition Related to Completion of Financing Event [Member]
Stock Option Activity [Abstract]
Stock-based compensation expense						$ 500
Number of Options [Roll Forward]
Granted (in shares)						205,000