Note 2 - Investments and Fair Value Measurement (Details Textual) - USD ($) $ in Thousands |
3 Months Ended | 9 Months Ended | 12 Months Ended | ||
|---|---|---|---|---|---|
Sep. 30, 2020 |
Sep. 30, 2019 |
Sep. 30, 2020 |
Sep. 30, 2019 |
Dec. 31, 2019 |
|
| Other than Temporary Impairment Losses, Investments, Available-for-sale Securities, Total | $ 0 | $ 0 | |||
| Debt Securities, Available-for-sale, Realized Gain (Loss), Total | $ 0 | $ 0 | 0 | $ 0 | |
| OCI, Debt Securities, Available-for-Sale, Transfer from Held-to-Maturity, Gain (Loss), before Adjustment, after Tax | $ 0 | $ 0 | $ 0 | $ 0 | |