| Note 4 - Investments (Details Textual) $ in Thousands | 3 Months Ended | 
|---|---|
| Mar. 31, 2023  USD ($) | |
| Debt Securities, Available-for-Sale, Unrealized Loss Position, Number of Positions | 59 | 
| Debt Securities, Available for Sale, Other than Temporary Impairment | $ 0 | 
| X | ||||||||||
| 
- Definition Represents other than temporary impairment of debt securities available for sale. No definition available. 
 | 
| X | ||||||||||
| 
- Definition Number of investments in debt securities measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale), in unrealized loss position, without allowance for credit loss. Includes beneficial interest in securitized financial asset. Reference 1: http://fasb.org/us-gaap/role/ref/otherTransitionRef 
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