Note 4 - Balance Sheet Components - Cash and Cash Equivalents and Investments (Details) - USD ($) $ in Thousands	Sep. 30, 2024	Dec. 31, 2023	Sep. 30, 2023	Dec. 31, 2022
Cash and Cash Equivalents, at Carrying Value	$ 22,035		$ 33,159
Cash and cash equivalents	22,035	$ 34,755	$ 33,238	$ 46,013
Gross unrealized gains	27
Gross unrealized losses	0	(1)
Short-term investments	36,676	4,958
Investments and Cash	58,684	39,714
Investments and Cash, Fair Value Disclosure	58,711	39,713
US Treasury Securities [Member]
Cash and cash equivalents	0
Amortized Cost	33,997	4,959
Gross unrealized gains	22
Gross unrealized losses	0	(1)
Estimated Fair Value	34,019	4,958
Short-term investments	34,019	4,958
Commercial Paper, Not Included with Cash and Cash Equivalents [Member]
Cash and cash equivalents	0
Amortized Cost	2,652
Gross unrealized gains	5
Gross unrealized losses	0
Estimated Fair Value	2,657
Short-term investments	2,657
Cash [Member]
Cash and Cash Equivalents, at Carrying Value	3,477	3,352
Money market funds, Fair Value	3,477	3,352
Cash and cash equivalents	3,477	3,352
Money Market Funds [Member]
Cash and Cash Equivalents, at Carrying Value	18,558	31,403
Money market funds, Fair Value	18,558	31,403
Cash and cash equivalents	$ 18,558	$ 31,403