Note 3 - Cash and Investments - Schedule of Cash and Cash Equivalents (Details) - USD ($) $ in Thousands	Sep. 30, 2023	Dec. 31, 2022	Sep. 30, 2022	Dec. 31, 2021
Cash	$ 1,541	$ 2,243
Cash equivalents (see detail in Note 4)	7,275	33,171
Restricted cash (see detail in Note 4)	222	221
Total cash, cash equivalents and restricted cash	9,038	35,635	$ 26,386	$ 40,086
Short-term investments	22,796	7
Total cash, cash equivalents, restricted cash and short-term investments	$ 31,834	$ 35,642