Note 4 - Balance Sheet Components - Cash and Cash Equivalents and Investments (Details) - USD ($) $ in Thousands	Mar. 31, 2024	Dec. 31, 2023	Mar. 31, 2023	Dec. 31, 2022
Cash and Cash Equivalents, at Carrying Value	$ 26,735		$ 46,831
Cash and cash equivalents	26,735	$ 34,755	$ 48,434	$ 46,013
Gross Unrealized Loss	(10)	(1)
Short-term investments	9,929	4,958
Investments and Cash	36,674	39,714
Investments and Cash, Fair Value Disclosure	36,664	39,713
US Treasury Securities [Member]
Cash and cash equivalents	4,947
Amortized Cost	14,886	4,959
Gross Unrealized Loss	(10)	(1)
Estimated Fair Value	14,876	4,958
Short-term investments	9,929	4,958
Cash [Member]
Cash and Cash Equivalents, at Carrying Value	4,078	3,352
Money market funds, Fair Value	4,078	3,352
Cash and cash equivalents	4,078	3,352
Money Market Funds [Member]
Cash and Cash Equivalents, at Carrying Value	17,710	31,403
Money market funds, Fair Value	17,710	31,403
Cash and cash equivalents	$ 17,710	$ 31,403