Note 3 - Investments  | 
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| Notes to Financial Statements | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Investment [Text Block] | 
    Note 3 - Investments 
 As of March 31, 2024, the Company had two money market accounts and available-for-sale investments with contractual maturities of three months or less categorized as cash and cash equivalents and available-for-sale investments with contractual maturities of three months to one year categorized as investments invested as follows: 
 
 
 As of March 31, 2024, there were no available-for-sale securities in an unrealized-loss position. U.S. Treasury Bills classified as investments on the condensed consolidated balance sheet as of March 31, 2024 were approximately $986,000. 
 As of December 31, 2023 the Company had two money market accounts and available-for-sale investments with contractual maturities of three months or less categorized as cash and cash equivalents as follows: 
 
 
 As of December 31, 2023, there were no available-for-sale securities in an unrealized-loss position. There were no U.S. Treasury Bills classified as investments on the condensed consolidated balance sheet as of December 31, 2023. 
 See Note 2 for additional discussion regarding the Company’s fair value measurements. 
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