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Consolidated Schedule of Investments - Investments (Details) (Parentheticals) | Dec. 31, 2023 | Dec. 31, 2022
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NAV % | 218.90% | 226.10%
Investment, Affiliated Issuer, Controlled [Member] | Consumer-related Technologies [Member] |  |
NAV % | 1.60% |
Investment, Affiliated Issuer, Controlled [Member] | Consumer-related Technologies [Member] | Debt Securities [Member] |  |
NAV % | 4.40% |
Investment, Affiliated Issuer, Controlled [Member] | Life Science [Member] | Other Investments [Member] |  |
NAV % | 1.90% |
Investment, Affiliated Issuer, Controlled [Member] | Technology Sector [Member] | Equity Securities [Member] |  |
NAV % | 0.90% |
Investment, Affiliated Issuer, Noncontrolled [Member] | Debt Securities [Member] |  |
NAV % | 0.30% |
Investment, Affiliated Issuer, Noncontrolled [Member] | Life Science [Member] | Equity Securities [Member] |  |
NAV % | 0.00% |
Investment, Affiliated Issuer, Noncontrolled [Member] | Life Science [Member] | Warrant [Member] |  |
NAV % | 0.00% |
Investment, Unaffiliated Issuer [Member] |  |
NAV % | 214.20% | 226.10%
Investment, Unaffiliated Issuer [Member] | Debt Securities [Member] |  |
NAV % | 205.00% | 215.50%
Investment, Unaffiliated Issuer [Member] | Equity Securities [Member] |  |
NAV % | 1.50% | 0.80%
Investment, Unaffiliated Issuer [Member] | Warrant [Member] |  |
NAV % | 7.60% | 9.40%
Investment, Unaffiliated Issuer [Member] | Other Long-Term Investments [Member] |  |
NAV % |  | 0.40%
Investment, Unaffiliated Issuer [Member] | Life Science [Member] | Debt Securities [Member] |  |
NAV % | 75.60% | 99.70%
Investment, Unaffiliated Issuer [Member] | Life Science [Member] | Warrant [Member] |  |
NAV % |  | 3.10%
Investment, Unaffiliated Issuer [Member] | Life Science [Member] | Other Investments [Member] |  |
NAV % | 0.10% |
Investment, Unaffiliated Issuer [Member] | Technology Sector [Member] | Debt Securities [Member] |  |
NAV % | 83.30% | 81.40%
Investment, Unaffiliated Issuer [Member] | Technology Sector [Member] | Warrant [Member] |  |
NAV % | 4.50% | 5.10%
Investment, Unaffiliated Issuer [Member] | Healthcare Information and Services Segment [Member] | Debt Securities [Member] |  |
NAV % | 21.50% |
Investment, Unaffiliated Issuer [Member] | Healthcare Information and Services Segment [Member] | Warrant [Member] |  |
NAV % | 0.60% |
Investment, Unaffiliated Issuer [Member] | Life Science Segment [Member] | Warrant [Member] |  |
NAV % | 2.30% |
Investment, Unaffiliated Issuer [Member] | Sustainability Segment [Member] | Debt Securities [Member] |  |
NAV % | 24.60% | 26.30%
Investment, Unaffiliated Issuer [Member] | Sustainability Segment [Member] | Warrant [Member] |  |
NAV % | 0.20% | 0.60%
Investment, Unaffiliated Issuer [Member] | Healthcare Sector [Member] | Debt Securities [Member] |  |
NAV % |  | 8.10%
Investment, Unaffiliated Issuer [Member] | Healthcare Sector [Member] | Warrant [Member] |  |
NAV % |  | 0.60%

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