Consolidated Schedule of Investments - Investments (Details) (Parentheticals)	Dec. 31, 2023	Dec. 31, 2022
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%