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Note 6 - Fair Value (Details Textual) $ / shares in Units, $ in Thousands | 3 Months Ended | 6 Months Ended |
--- | --- | --- | ---
Jun. 30, 2026 USD ($) $ / shares | Jun. 30, 2025 USD ($) | Jun. 30, 2026 USD ($) $ / shares | Jun. 30, 2025 USD ($) | Jun. 30, 2022
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Transfers out of Level 3 | $ 89 | $ 0 | $ 89 |  |
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset Transfers Into Level 3 | 0 |  | 0 | $ 0 |
Unrealized Gain (Loss) on Investments | (38,533) | $ (22,156) | (43,133) | (54,313) |
Warrant [Member] |  |  |  |  |
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Transfers out of Level 3 | 89 |  | 89 |  |
Equity Securities [Member] |  |  |  |  |
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Transfers out of Level 3 | (0) |  | (0) |  |
Fair Value, Inputs, Level 3 [Member] | Warrant [Member] |  |  |  |  |
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Transfers out of Level 3 | $ 100 |  | 100 |  |
Unrealized Gain (Loss) on Investments |  |  | 100 | 3,900 |
Fair Value, Inputs, Level 3 [Member] | Debt Securities [Member] |  |  |  |  |
Unrealized Gain (Loss) on Investments |  |  | 27,400 | 45,500 |
Fair Value, Inputs, Level 3 [Member] | Equity Securities [Member] |  |  |  |  |
Unrealized Gain (Loss) on Investments |  |  | $ 20,600 | $ 14,700 |
The 2027 Notes [Member] | Fair Value, Inputs, Level 3 [Member] |  |  |  |  |
Debt Instrument, Share Price (in dollars per share) | $ / shares | $ 24.83 |  | $ 24.83 |  |
Debt Instrument, Fair Value Disclosure | $ 57,100 |  | $ 57,100 |  |
The 2028 Notes [Member] | Fair Value, Inputs, Level 3 [Member] |  |  |  |  |
Debt Instrument, Fair Value Disclosure | 57,100 |  | 57,100 |  |
The 2031 Convertible Notes [Member] | Fair Value, Inputs, Level 3 [Member] |  |  |  |  |
Debt Instrument, Fair Value Disclosure | 2,700 |  | 2,700 |  |
The 2030 Convertible Notes [Member] | Fair Value, Inputs, Level 3 [Member] |  |  |  |  |
Debt Instrument, Fair Value Disclosure | $ 16,200 |  | $ 16,200 |  |
Measurement Input, Hypothetical Market Yields [Member] |  |  |  |  |
Debt Instrument, Measurement Input |  |  |  |  | 0.25

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