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Note 4 - Investments - Investments (Details) - USD ($) $ in Thousands	Mar. 31, 2025	Dec. 31, 2024
Investments at cost	$ 790,592	$ 766,774
Investments at fair value	689,553	697,891
Biotechnology Sector [Member]
Investments at cost	138,360	118,221
Investments at fair value	116,174	97,562
Medical Device Sector [Member]
Investments at cost	220,360	213,564
Investments at fair value	192,105	205,634
Communications Sector [Member]
Investments at cost	518	11,711
Investments at fair value	3,547	14,763
Consumer-related Sector [Member]
Investments at cost	74,805	74,421
Investments at fair value	27,362	36,667
Data Storage Sector [Member]
Investments at cost	417	417
Investments at fair value	322	350
Internet and Media Sector [Member]
Investments at cost	329	329
Investments at fair value	911	999
Networking Sector [Member]
Investments at cost	10,076	10,070
Investments at fair value	9,826	9,827
Semiconductor Sector [Member]
Investments at cost	45	45
Investments at fair value	0	0
Software Sector [Member]
Investments at cost	161,916	154,040
Investments at fair value	159,213	151,043
Energy Efficiency [Member]
Investments at cost	9,824	9,818
Investments at fair value	9,713	9,712
Other Sustainability Sector [Member]
Investments at cost	65,329	66,151
Investments at fair value	64,109	66,079
Diagnostics Sector [Member]
Investments at cost	17,252	16,704
Investments at fair value	14,661	13,701
Other Healthcare Sector [Member]
Investments at cost	39,552	39,533
Investments at fair value	40,166	40,144
Software, Healthcare Information and Service [Member]
Investments at cost	51,809	51,750
Investments at fair value	51,444	51,410
Debt [Member]
Investments at cost	699,761	678,167
Investments at fair value	643,567	638,779
Warrant [Member]
Investments at cost	16,120	15,956
Investments at fair value	18,603	18,277
Other Debt Obligations [Member]
Investments at cost	36,723	36,709
Investments at fair value	13,697	14,637
Equity Securities [Member]
Investments at cost	37,988	35,942
Investments at fair value	$ 13,686	$ 26,198

X

- Definition

Cost of the investment.

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