Note 4 - Balance Sheet Components - Cash and Cash Equivalents and Investments (Details) - USD ($) $ in Thousands	Sep. 30, 2025	Dec. 31, 2024
Cash and cash equivalents	$ 16,880	$ 25,229
Gross unrealized gains	0	8
Gross unrealized losses	(2)	(4)
Short-term investments	11,913	26,494
Investments and Cash	28,795	51,719
Investments and Cash, Fair Value Disclosure	28,793	51,723
US Treasury Securities [Member]
Cash and cash equivalents	4,979	0
Amortized Cost	16,894	23,802
Gross unrealized gains	0	7
Gross unrealized losses	(2)	(4)
Estimated Fair Value	16,892	23,805
Short-term investments	11,913	23,805
Commercial Paper, Not Included with Cash and Cash Equivalents [Member]
Cash and cash equivalents	2,653	0
Amortized Cost	2,653	2,688
Gross unrealized gains	0	1
Gross unrealized losses	0	0
Estimated Fair Value	2,653	2,689
Short-term investments	0	2,689
Cash [Member]
Cash and Cash Equivalents, at Carrying Value	3,521	8,740
Money market funds, Fair Value	3,521	8,740
Cash and cash equivalents	3,521	8,740
Money Market Funds [Member]
Cash and Cash Equivalents, at Carrying Value	5,727	16,489
Money market funds, Fair Value	5,727	16,489
Cash and cash equivalents	$ 5,727	$ 16,489