Note 2 - Investments and Fair Value Measurement (Details Textual) - USD ($) $ in Thousands |
12 Months Ended | ||
|---|---|---|---|
Dec. 31, 2021 |
Dec. 31, 2020 |
Dec. 31, 2019 |
|
| Debt Securities, Available-for-sale, Realized Gain (Loss), Total | $ 0 | $ 0 | $ 0 |
| Debt Securities, Available-for-sale, Total | 0 | ||
| OCI, Debt Securities, Available-for-Sale, Transfer from Held-to-Maturity, Gain (Loss), before Adjustment, after Tax | $ 0 | 0 | |
| Other-than-temporary Impairment Loss, Debt Securities, Available-for-sale, Total | $ 0 | ||