Income Taxes (Schedule of Deferred Tax Assets) (Details) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Deferred tax assets:
Net operating loss carryovers	$ 45,090	$ 27,446
Stock compensation and other	2,444	2,037
Change in fair value of warrant liabilities	59	57
Amortization of license	12,804	9,454
Lease liability	825	746
Accruals and reserves	504	519
Startup costs	7	7
Debt Issuance Costs	0	21
Tax credits	5,743	2,746
Total deferred tax assets	67,476	43,033
Less valuation allowance	(67,073)	(42,608)
Net deferred tax assets	403	425
Deferred tax liabilities:
Right of use asset	(403)	(425)
Total deferred tax assets, net	$ 0	$ 0