Note 17 - Income Taxes - Components of Deferred Tax Assets (Details) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Net operating loss carry-forwards	$ 14,161	$ 6,924	$ 43,822
Research and development tax credits	2,497	1,591	3,357
Capitalized research and development	4,534	4,773	2,326
Sale of future royalties	7,178	7,486	8,383
Lease Liability	1,695	492
Accruals, reserves and other	1,327	1,253	714
Total deferred tax assets	31,392	22,519	58,602
Valuation allowance	(21,952)	(13,365)	(48,626)
Deferred tax assets net of valuation allowance	9,440	9,154	9,976
Intangible assets	(7,832)	(8,730)	(9,976)
Right-of-use assets	(1,608)	(424)
Total deferred tax liabilities	(9,440)	(9,154)	(9,976)
Net deferred tax assets