Income Taxes (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020
Loss before income taxes
U.S. operations	$ 98,776	$ 67,475
Loss before income taxes	98,776	67,475
Gross deferred tax assets:
Net operating loss carryforwards	81,719	59,819
Accrued expenses	272	219
Amortization of intangibles	251
Stock-based compensation	5,944	4,270
Research and development and other credits and other carryforwards	16,216	11,906
Lease Liability	610	879
Capitalized research and development expenses	11,437	15,891
Unrealized income		12
Other	9	4
Total gross deferred tax assets	116,458	93,000
Gross deferred tax liabilities:
ROU Asset	(399)	(569)
Depreciation	(99)	(252)
Unrealized income	(212)
Total gross deferred tax liabilities	(710)	(821)
Net deferred tax assets	115,748	92,179
Less: valuation allowance	(115,748)	(92,179)
Increase (decrease) in valuation allowance	23,600	39,700
Unrecognized tax benefit	0	0
Liability for uncertain tax positions	0	0
Interest and penalties accrued related to unrecognized tax benefits	$ 0	$ 0
Reconciliation of income tax expense (benefit) at the statutory federal income tax rate and income taxes
Federal income tax expense at statutory rate (as a percent)	21.00%	21.00%
Permanent items (as a percent)	(0.70%)	(0.70%)
State income tax, net of federal benefit (as a percent)	2.20%	7.60%
R&D tax credits (as a percent)	4.30%	4.70%
Change in state tax rate (as a percent)	(2.80%)
Capitalized research and development expenses (as a percent)		26.20%
Change in valuation allowance (as a percent)	(24.00%)	(58.80%)
Effective income tax rate (as a percent)	0.00%	0.00%
Federal
Loss before income taxes
Net operating loss carry forwards available to offset future federal and state taxable income	$ 303,300	$ 212,000
Net operating loss carry forwards subject to expiration	128,100
State
Loss before income taxes
Net operating loss carry forwards available to offset future federal and state taxable income	253,000	$ 209,500
Research and development | Federal
Loss before income taxes
Tax credit carryovers	15,800
Research and development | State
Loss before income taxes
Tax credit carryovers	$ 400