Note 1 - Organization and Summary of Significant Accounting Policies - Fair Value Hierarchy for Assets and Liabilities (Details) - USD ($) $ in Thousands	Dec. 31, 2023	Dec. 31, 2022
Corporate, municipal debt and treasury securities	$ 5,230	$ 4,973
Total assets	28,278	22,469
Corporate Debt Securities [Member]
Corporate, municipal debt and treasury securities	5,230	4,973
Fair Value, Inputs, Level 1 [Member]
Corporate, municipal debt and treasury securities		4,973
Total assets	28,278	22,469
Fair Value, Inputs, Level 1 [Member] | Corporate Debt Securities [Member]
Corporate, municipal debt and treasury securities	5,230
Money Market Funds [Member]
Money market accounts	23,048	17,496
Money Market Funds [Member] | Fair Value, Inputs, Level 1 [Member]
Money market accounts	$ 23,048	$ 17,496