Note 5 - Transactions With Affiliated Companies - Investments in Controlled Affiliated Companies (Details) - USD ($) $ in Thousands	3 Months Ended
Mar. 31, 2024	Mar. 31, 2023
Investments, fair value	$ 709,085
Net unrealized appreciation (depreciation) on investments	(3,960)	$ (7,537)
Net realized gain (loss) on investments	8	(168)
Investments, fair value	711,116
Interest Income, Operating, Paid in Kind	1,382	1,204
Investment, Affiliated Issuer, Noncontrolled [Member]
Investments, fair value	1,132	0
Purchases	15	0
Reductions	0	(0)
Transfers in/(out) at fair value	0	0
Discount accretion	0	0
Net unrealized appreciation (depreciation) on investments	11,433	846
Net realized gain (loss) on investments	(3)	0
Investments, fair value	12,577	846
Interest income	0	0
Reductions	0	0
Investment, Affiliated Issuer, Noncontrolled [Member] \| Aulea Medical, Inc. [Member]
Investments, fair value	0
Purchases	3
Reductions	0
Transfers in/(out) at fair value	0
Discount accretion	0
Net unrealized appreciation (depreciation) on investments	0
Net realized gain (loss) on investments	(3)
Investments, fair value	0
Interest income	0
Reductions	0
Investment, Affiliated Issuer, Noncontrolled [Member] \| Cadrenal Therapeutics, Inc. [Member]
Investments, fair value		0
Purchases		0
Reductions		(0)
Transfers in/(out) at fair value		0
Discount accretion		0
Net unrealized appreciation (depreciation) on investments		846
Net realized gain (loss) on investments		0
Investments, fair value		846
Interest income		0
Reductions		0
Investment, Affiliated Issuer, Noncontrolled [Member] \| Evelo Biosciences, Inc. [Member] \| Investment One [Member]
Investments, fair value	222
Purchases	0
Reductions	0
Transfers in/(out) at fair value	0
Discount accretion	0
Net unrealized appreciation (depreciation) on investments	2,568
Net realized gain (loss) on investments	0
Investments, fair value	2,790
Interest income	0
Reductions	0
Investment, Affiliated Issuer, Noncontrolled [Member] \| Evelo Biosciences, Inc. [Member] \| Investment Two [Member]
Investments, fair value	336
Purchases	12
Reductions	0
Transfers in/(out) at fair value	0
Discount accretion	0
Net unrealized appreciation (depreciation) on investments	3,859
Net realized gain (loss) on investments	0
Investments, fair value	4,207
Interest income	0
Reductions	0
Investment, Affiliated Issuer, Noncontrolled [Member] \| Evelo Biosciences, Inc. [Member] \| Investment Three [Member]
Investments, fair value	133
Purchases	0
Reductions	0
Transfers in/(out) at fair value	0
Discount accretion	0
Net unrealized appreciation (depreciation) on investments	1,541
Net realized gain (loss) on investments	0
Investments, fair value	1,674
Interest income	0
Reductions	0
Investment, Affiliated Issuer, Noncontrolled [Member] \| Evelo Biosciences, Inc. [Member] \| Investment Four [Member]
Investments, fair value	133
Purchases	0
Reductions	0
Transfers in/(out) at fair value	0
Discount accretion	0
Net unrealized appreciation (depreciation) on investments	1,541
Net realized gain (loss) on investments	0
Investments, fair value	1,674
Interest income	0
Reductions	0
Investment, Affiliated Issuer, Noncontrolled [Member] \| Evelo Biosciences, Inc. [Member] \| Investment Five [Member]
Investments, fair value	88
Purchases	0
Reductions	0
Transfers in/(out) at fair value	0
Discount accretion	0
Net unrealized appreciation (depreciation) on investments	1,028
Net realized gain (loss) on investments	0
Investments, fair value	1,116
Interest income	0
Reductions	0
Investment, Affiliated Issuer, Noncontrolled [Member] \| Evelo Biosciences, Inc. [Member] \| Investment Six [Member]
Investments, fair value	88
Purchases	0
Reductions	0
Transfers in/(out) at fair value	0
Discount accretion	0
Net unrealized appreciation (depreciation) on investments	1,028
Net realized gain (loss) on investments	0
Investments, fair value	1,116
Interest income	0
Reductions	0
Investment, Affiliated Issuer, Noncontrolled [Member] \| Evelo Biosciences, Inc. [Member] \| Investment Seven [Member]
Investments, fair value	132
Purchases	0
Reductions	0
Transfers in/(out) at fair value	0
Discount accretion	0
Net unrealized appreciation (depreciation) on investments	(132)
Net realized gain (loss) on investments	0
Investments, fair value	0
Interest income	0
Reductions	0
Investment, Affiliated Issuer, Controlled [Member]
Investments, fair value	14,223
Purchases	977
Reductions	547
Transfers in/(out) at fair value	0
Discount accretion	4
Net unrealized appreciation (depreciation) on investments	(1,179)	0
Net realized gain (loss) on investments	0
Investments, fair value	13,644
Interest income	11	0
Reductions	(547)
Interest Income, Operating, Paid in Kind	166	$ 0
Investment, Affiliated Issuer, Controlled [Member] \| Investment [Member]
Interest income	177
Investment, Affiliated Issuer, Controlled [Member] \| Better Place Forests Co. [Member] \| Investment One [Member]
Investments, fair value	3,339
Purchases	0
Reductions	(0)
Transfers in/(out) at fair value	0
Discount accretion	2
Net unrealized appreciation (depreciation) on investments	3
Net realized gain (loss) on investments	0
Investments, fair value	3,455
Interest income	116
Reductions	0
Interest Income, Operating, Paid in Kind	111
Investment, Affiliated Issuer, Controlled [Member] \| Better Place Forests Co. [Member] \| Investment Two [Member]
Investments, fair value	1,630
Purchases	0
Reductions	(0)
Transfers in/(out) at fair value	0
Discount accretion	2
Net unrealized appreciation (depreciation) on investments	1
Net realized gain (loss) on investments	0
Investments, fair value	1,688
Interest income	61
Reductions	0
Interest Income, Operating, Paid in Kind	55
Investment, Affiliated Issuer, Controlled [Member] \| Better Place Forests Co. [Member] \| Investment Three [Member]
Investments, fair value	3,024
Purchases	750
Reductions	(0)
Transfers in/(out) at fair value	0
Discount accretion	0
Net unrealized appreciation (depreciation) on investments	(1,118)
Net realized gain (loss) on investments	0
Investments, fair value	2,656
Interest income	0
Reductions	0
Interest Income, Operating, Paid in Kind	0
Investment, Affiliated Issuer, Controlled [Member] \| HIMV LLC [Member]
Investments, fair value	6,230
Purchases	227
Reductions	547
Transfers in/(out) at fair value	0
Discount accretion	0
Net unrealized appreciation (depreciation) on investments	(65)
Net realized gain (loss) on investments	0
Investments, fair value	5,845
Interest income	0
Reductions	(547)
Interest Income, Operating, Paid in Kind	$ 0

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