Note 4 - Balance Sheet Components - Cash and Cash Equivalents and Investments (Details) - USD ($) $ in Thousands	Jun. 30, 2024	Dec. 31, 2023	Jun. 30, 2023	Dec. 31, 2022
Cash and cash equivalents	$ 43,285	$ 34,755	$ 43,277	$ 46,013
Gross Unrealized Loss	(16)	(1)
Short-term investments	19,308	4,958
Investments and Cash	62,609	39,714
Investments and Cash, Fair Value Disclosure	62,593	39,713
US Treasury Securities [Member]
Cash and cash equivalents	0
Amortized Cost	19,324	4,959
Gross Unrealized Loss	(16)	(1)
Estimated Fair Value	19,308	4,958
Short-term investments	19,308	4,958
Cash [Member]
Cash and Cash Equivalents, at Carrying Value	5,285	3,352
Money market funds, Fair Value	5,285	3,352
Cash and cash equivalents	5,285	3,352
Money Market Funds [Member]
Cash and Cash Equivalents, at Carrying Value	38,000	31,403
Money market funds, Fair Value	38,000	31,403
Cash and cash equivalents	$ 38,000	$ 31,403