Note 4 - Balance Sheet Components (Details Textual) - USD ($)	3 Months Ended		9 Months Ended
	Sep. 30, 2024	Sep. 30, 2023	Sep. 30, 2024	Sep. 30, 2023	Dec. 31, 2023
Accounts Receivable, after Allowance for Credit Loss	$ 590,000		$ 590,000		$ 3,000,000
Accounts Receivable, Allowance for Credit Loss	0		0		0
Unbilled Receivables, Current	3,085,000		3,085,000		0
Depreciation	1,000,000	$ 1,000,000	2,800,000	$ 2,800,000
Tangible Asset Impairment Charges	0	0	0	0
Prepaid Expense Other, Noncurrent	60,116,000		60,116,000		0
Operating Lease, Right-of-Use Asset	21,536,000		21,536,000		24,840,000
Amortization of Intangible Assets	100,000	$ 200,000	500,000	$ 500,000
Goodwill	4,508,000		4,508,000		4,508,000
Goodwill, Impairment Loss			$ 0
Developed Technology Rights [Member]
Finite-Lived Intangible Asset, Remaining Life (Year)			5 years 1 month 6 days
Intellectual Property [Member]
Finite-Lived Intangible Asset, Remaining Life (Year)			3 years 3 months 18 days
Facility in Burlingame, California [Member]
Operating Lease, Right-of-Use Asset					3,100,000
BARDA [Member]
Unbilled Receivables, Current	3,100,000		$ 3,100,000		0
Government Contract [Member]
Accounts Receivable, after Allowance for Credit Loss	550,000		550,000
Deferred Revenue, Current	65,447,000		65,447,000		$ 0
Royalty [Member]
Prepaid Royalties	$ 40,000		$ 40,000