Note 4 - Investments and Fair Value Measurements - Investments Measured at Fair Value (Details) - USD ($) $ in Thousands | Jun. 30, 2023 | Dec. 31, 2022 |
Debt securities, held-to-maturity, fair value | $ 40,773 | $ 88,964 |
Available-for-sale debt securities, at fair value (amortized cost $58,106 at June 30, 2023 and $59,191 at December 31, 2022) | 57,021 | 58,254 |
Corporate Debt Securities [Member] | | |
Debt securities, held-to-maturity, fair value | 36,883 | 59,673 |
Available-for-sale debt securities, at fair value (amortized cost $58,106 at June 30, 2023 and $59,191 at December 31, 2022) | 25,511 | 26,888 |
US Treasury Securities [Member] | | |
Debt securities, held-to-maturity, fair value | 3,453 | 23,987 |
Available-for-sale debt securities, at fair value (amortized cost $58,106 at June 30, 2023 and $59,191 at December 31, 2022) | 30,058 | 29,923 |
Debt Security, Government, Non-US [Member] | | |
Debt securities, held-to-maturity, fair value | 0 | 4,999 |
Available-for-sale debt securities, at fair value (amortized cost $58,106 at June 30, 2023 and $59,191 at December 31, 2022) | 1,452 | 1,443 |
Certificates of Deposit [Member] | | |
Debt securities, held-to-maturity, fair value | 437 | 305 |
Fair Value, Recurring [Member] | | |
Debt securities, held-to-maturity, fair value | 40,773 | 88,964 |
Available-for-sale debt securities, at fair value (amortized cost $58,106 at June 30, 2023 and $59,191 at December 31, 2022) | 57,021 | 58,254 |
Mortgage loans | 46 | 297 |
Total | 97,840 | 147,515 |
Liabilities, fair value | 443 | 566 |
Fair Value, Recurring [Member] | Corporate Debt Securities [Member] | | |
Debt securities, held-to-maturity, fair value | 36,883 | 59,673 |
Available-for-sale debt securities, at fair value (amortized cost $58,106 at June 30, 2023 and $59,191 at December 31, 2022) | 25,511 | 26,888 |
Fair Value, Recurring [Member] | US Treasury Securities [Member] | | |
Debt securities, held-to-maturity, fair value | 3,453 | 23,987 |
Available-for-sale debt securities, at fair value (amortized cost $58,106 at June 30, 2023 and $59,191 at December 31, 2022) | 30,058 | 29,923 |
Fair Value, Recurring [Member] | Debt Security, Government, Non-US [Member] | | |
Debt securities, held-to-maturity, fair value | 0 | 4,999 |
Available-for-sale debt securities, at fair value (amortized cost $58,106 at June 30, 2023 and $59,191 at December 31, 2022) | 1,452 | 1,443 |
Fair Value, Recurring [Member] | Certificates of Deposit [Member] | | |
Debt securities, held-to-maturity, fair value | 437 | 305 |
Fair Value, Recurring [Member] | Public Warrants [Member] | | |
Liabilities, fair value | 230 | 230 |
Fair Value, Recurring [Member] | Private Placement Warrants [Member] | | |
Liabilities, fair value | 117 | 117 |
Fair Value, Recurring [Member] | Sponsor Covered Shares [Member] | | |
Liabilities, fair value | 96 | 219 |
Fair Value, Recurring [Member] | Fair Value, Inputs, Level 1 [Member] | | |
Debt securities, held-to-maturity, fair value | 3,453 | 23,987 |
Available-for-sale debt securities, at fair value (amortized cost $58,106 at June 30, 2023 and $59,191 at December 31, 2022) | 30,058 | 29,923 |
Mortgage loans | 0 | 0 |
Total | 33,511 | 53,910 |
Liabilities, fair value | 230 | 230 |
Fair Value, Recurring [Member] | Fair Value, Inputs, Level 1 [Member] | Corporate Debt Securities [Member] | | |
Debt securities, held-to-maturity, fair value | 0 | 0 |
Available-for-sale debt securities, at fair value (amortized cost $58,106 at June 30, 2023 and $59,191 at December 31, 2022) | 0 | 0 |
Fair Value, Recurring [Member] | Fair Value, Inputs, Level 1 [Member] | US Treasury Securities [Member] | | |
Debt securities, held-to-maturity, fair value | 3,453 | 23,987 |
Available-for-sale debt securities, at fair value (amortized cost $58,106 at June 30, 2023 and $59,191 at December 31, 2022) | 30,058 | 29,923 |
Fair Value, Recurring [Member] | Fair Value, Inputs, Level 1 [Member] | Debt Security, Government, Non-US [Member] | | |
Debt securities, held-to-maturity, fair value | 0 | 0 |
Available-for-sale debt securities, at fair value (amortized cost $58,106 at June 30, 2023 and $59,191 at December 31, 2022) | 0 | 0 |
Fair Value, Recurring [Member] | Fair Value, Inputs, Level 1 [Member] | Certificates of Deposit [Member] | | |
Debt securities, held-to-maturity, fair value | 0 | 0 |
Fair Value, Recurring [Member] | Fair Value, Inputs, Level 1 [Member] | Public Warrants [Member] | | |
Liabilities, fair value | 230 | 230 |
Fair Value, Recurring [Member] | Fair Value, Inputs, Level 1 [Member] | Private Placement Warrants [Member] | | |
Liabilities, fair value | 0 | 0 |
Fair Value, Recurring [Member] | Fair Value, Inputs, Level 1 [Member] | Sponsor Covered Shares [Member] | | |
Liabilities, fair value | 0 | 0 |
Fair Value, Recurring [Member] | Fair Value, Inputs, Level 2 [Member] | | |
Debt securities, held-to-maturity, fair value | 37,320 | 64,977 |
Available-for-sale debt securities, at fair value (amortized cost $58,106 at June 30, 2023 and $59,191 at December 31, 2022) | 26,963 | 28,331 |
Mortgage loans | 0 | 0 |
Total | 64,283 | 93,308 |
Liabilities, fair value | 117 | 117 |
Fair Value, Recurring [Member] | Fair Value, Inputs, Level 2 [Member] | Corporate Debt Securities [Member] | | |
Debt securities, held-to-maturity, fair value | 36,883 | 59,673 |
Available-for-sale debt securities, at fair value (amortized cost $58,106 at June 30, 2023 and $59,191 at December 31, 2022) | 25,511 | 26,888 |
Fair Value, Recurring [Member] | Fair Value, Inputs, Level 2 [Member] | US Treasury Securities [Member] | | |
Debt securities, held-to-maturity, fair value | 0 | 0 |
Available-for-sale debt securities, at fair value (amortized cost $58,106 at June 30, 2023 and $59,191 at December 31, 2022) | 0 | 0 |
Fair Value, Recurring [Member] | Fair Value, Inputs, Level 2 [Member] | Debt Security, Government, Non-US [Member] | | |
Debt securities, held-to-maturity, fair value | 0 | 4,999 |
Available-for-sale debt securities, at fair value (amortized cost $58,106 at June 30, 2023 and $59,191 at December 31, 2022) | 1,452 | 1,443 |
Fair Value, Recurring [Member] | Fair Value, Inputs, Level 2 [Member] | Certificates of Deposit [Member] | | |
Debt securities, held-to-maturity, fair value | 437 | 305 |
Fair Value, Recurring [Member] | Fair Value, Inputs, Level 2 [Member] | Public Warrants [Member] | | |
Liabilities, fair value | 0 | 0 |
Fair Value, Recurring [Member] | Fair Value, Inputs, Level 2 [Member] | Private Placement Warrants [Member] | | |
Liabilities, fair value | 117 | 117 |
Fair Value, Recurring [Member] | Fair Value, Inputs, Level 2 [Member] | Sponsor Covered Shares [Member] | | |
Liabilities, fair value | 0 | 0 |
Fair Value, Recurring [Member] | Fair Value, Inputs, Level 3 [Member] | | |
Debt securities, held-to-maturity, fair value | 0 | 0 |
Available-for-sale debt securities, at fair value (amortized cost $58,106 at June 30, 2023 and $59,191 at December 31, 2022) | 0 | 0 |
Mortgage loans | 46 | 297 |
Total | 46 | 297 |
Liabilities, fair value | 96 | 219 |
Fair Value, Recurring [Member] | Fair Value, Inputs, Level 3 [Member] | Corporate Debt Securities [Member] | | |
Debt securities, held-to-maturity, fair value | 0 | 0 |
Available-for-sale debt securities, at fair value (amortized cost $58,106 at June 30, 2023 and $59,191 at December 31, 2022) | 0 | 0 |
Fair Value, Recurring [Member] | Fair Value, Inputs, Level 3 [Member] | US Treasury Securities [Member] | | |
Debt securities, held-to-maturity, fair value | 0 | 0 |
Available-for-sale debt securities, at fair value (amortized cost $58,106 at June 30, 2023 and $59,191 at December 31, 2022) | 0 | 0 |
Fair Value, Recurring [Member] | Fair Value, Inputs, Level 3 [Member] | Debt Security, Government, Non-US [Member] | | |
Debt securities, held-to-maturity, fair value | 0 | 0 |
Available-for-sale debt securities, at fair value (amortized cost $58,106 at June 30, 2023 and $59,191 at December 31, 2022) | 0 | 0 |
Fair Value, Recurring [Member] | Fair Value, Inputs, Level 3 [Member] | Certificates of Deposit [Member] | | |
Debt securities, held-to-maturity, fair value | 0 | 0 |
Fair Value, Recurring [Member] | Fair Value, Inputs, Level 3 [Member] | Public Warrants [Member] | | |
Liabilities, fair value | 0 | 0 |
Fair Value, Recurring [Member] | Fair Value, Inputs, Level 3 [Member] | Private Placement Warrants [Member] | | |
Liabilities, fair value | 0 | 0 |
Fair Value, Recurring [Member] | Fair Value, Inputs, Level 3 [Member] | Sponsor Covered Shares [Member] | | |
Liabilities, fair value | $ 96 | $ 219 |