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Note 4 - Investments - Investments (Details) - USD ($) $ in Thousands	Jun. 30, 2025	Dec. 31, 2024
Investments at cost	$ 745,848	$ 766,774
Investments at fair value	622,653	697,891
Biotechnology Sector [Member]
Investments at cost	120,283	118,221
Investments at fair value	84,043	97,562
Medical Device Sector [Member]
Investments at cost	239,170	213,564
Investments at fair value	209,087	205,634
Communications Sector [Member]
Investments at cost	517	11,711
Investments at fair value	3,532	14,763
Consumer-related Sector [Member]
Investments at cost	65,352	74,421
Investments at fair value	25,066	36,667
Data Storage Sector [Member]
Investments at cost	417	417
Investments at fair value	330	350
Internet and Media Sector [Member]
Investments at cost	329	329
Investments at fair value	605	999
Networking Sector [Member]
Investments at cost	364	10,070
Investments at fair value	121	9,827
Semiconductor Sector [Member]
Investments at cost	0	45
Investments at fair value	0	0
Software Sector [Member]
Investments at cost	165,371	154,040
Investments at fair value	158,536	151,043
Alternative Energy [Member]
Investments at cost	4,854	0
Investments at fair value	4,845	0
Energy Efficiency [Member]
Investments at cost	9,934	9,818
Investments at fair value	9,828	9,712
Other Sustainability Sector [Member]
Investments at cost	30,449	66,151
Investments at fair value	23,008	66,079
Diagnostics Sector [Member]
Investments at cost	17,350	16,704
Investments at fair value	9,940	13,701
Other Healthcare Sector [Member]
Investments at cost	39,575	39,533
Investments at fair value	42,194	40,144
Software, Healthcare Information and Service [Member]
Investments at cost	51,883	51,750
Investments at fair value	51,518	51,410
Debt [Member]
Investments at cost	636,261	678,167
Investments at fair value	579,171	638,779
Warrant [Member]
Investments at cost	15,565	15,956
Investments at fair value	21,629	18,277
Other Debt Obligations [Member]
Investments at cost	55,924	36,709
Investments at fair value	8,451	14,637
Equity Securities [Member]
Investments at cost	38,098	35,942
Investments at fair value	$ 13,402	$ 26,198

X

- Definition

Cost of the investment.

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