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Note 7 - Borrowings (Details Textual) $ / shares in Units, $ in Thousands									3 Months Ended		6 Months Ended		12 Months Ended
	May 23, 2025 USD ($)	Apr. 25, 2025	Apr. 17, 2025	Oct. 17, 2024 USD ($)	Jun. 21, 2024 USD ($)	Jun. 20, 2024	Jun. 19, 2024	May 24, 2023 USD ($)	Jun. 30, 2025 USD ($) $ / shares	Jun. 30, 2024 USD ($) $ / shares	Jun. 30, 2025 USD ($) $ / shares shares	Jun. 30, 2024 USD ($) $ / shares	Dec. 31, 2024 USD ($) $ / shares	Dec. 31, 2023 $ / shares	Jun. 29, 2023 USD ($)	Nov. 09, 2022 USD ($)	Jun. 15, 2022 USD ($) $ / shares	Mar. 30, 2021 USD ($) $ / shares	Apr. 21, 2020 USD ($)
Asset Coverage to Borrowings, Ratio, Percent											166.00%
Restricted Investments									$ 3,226		$ 3,226		$ 3,338
Long-Term Debt, Gross									427,669		427,669		472,078
Debt Instrument, Face Amount									$ 756,669		$ 756,669		$ 716,078
Share Price (in dollars per share) | $ / shares									$ 7.2	$ 12.04	$ 7.2	$ 12.04	$ 8.99	$ 13.17
Debt Instrument, Convertible, Maximum Beneficial Ownership Percentage				4.99%
Debt Conversion, Original Debt, Amount											$ 12,500	$ 0
Debt Instrument, Unamortized Discount (Premium) and Debt Issuance Costs, Net									$ 2,531		$ 2,531		$ 4,174
Conversion of 2031 Notes Into Common Stock [Member]
Debt Instrument, Convertible, Conversion Price (in dollars per share) | $ / shares									$ 7.79		$ 7.79
Debt Conversion, Original Debt, Amount											$ 12,500
Debt Conversion, Converted Instrument, Shares Issued (in shares) | shares											1,621,503
Debt Instrument, Unamortized Discount (Premium) and Debt Issuance Costs, Net									$ 800		$ 800
Key Facility [Member]
Line of Credit Facility, Maximum Borrowing Capacity, Accordian Feature															$ 150,000
Line of Credit Facility, Maximum Borrowing Capacity															$ 300,000
Line of Credit Facility, Advance Rate of Eligible Debt Investments															60.00%
Long-Term Debt, Weighted Average Interest Rate, over Time									7.60%	8.73%	7.60%	8.74%
Line of Credit Facility, Unused Capacity, Commitment Fee Percentage											0.75%
Line of Credit Facility, Current Borrowing Capacity									$ 150,000		$ 150,000		150,000
Line of Credit Facility, Remaining Borrowing Capacity									38,300		38,300		24,800
Long-Term Debt, Gross									0		0		0
Debt Instrument, Face Amount									$ 150,000		$ 150,000		$ 150,000
Key Facility [Member] | Prime Rate [Member]
Debt Instrument, Basis Spread on Variable Rate						0.10%	0.25%
Debt Instrument, Variable Rate									7.50%		7.50%		7.50%
NYL Facility [Member]
Line of Credit Facility, Maximum Borrowing Capacity								$ 250,000											$ 100,000
Line of Credit Facility, Current Borrowing Capacity									$ 69,000		$ 69,000		$ 69,000
Line of Credit Facility, Remaining Borrowing Capacity									200		200		8,400
Line of Credit Facility, Maximum Borrowing Capacity, Accordion Feature																			$ 200,000
Line of Credit Facility, Advance Rate																			67.00%
Line of Credit Facility, Change in Maximum Borrowing Capacity								$ 50,000
Debt Instrument, Interest Rate, Stated Percentage								4.60%
Long-Term Line of Credit									$ 181,000		$ 181,000		181,000
Line of Credit Facility, Interest Rate at Period End									6.55%	6.34%	6.55%	6.34%
Restricted Investments									$ 1,400		$ 1,400		1,400
Long-Term Debt, Gross									181,000		181,000		181,000
Debt Instrument, Face Amount									250,000		250,000		250,000
NYL Facility [Member] | Three Year I Curve [Member]
Debt Instrument, Basis Spread on Variable Rate		2.95%
Nuveen Facility [Member]
Line of Credit Facility, Maximum Borrowing Capacity, Accordian Feature					$ 200,000
Line of Credit Facility, Maximum Borrowing Capacity	$ 200,000				$ 100,000
Line of Credit Facility, Current Borrowing Capacity									110,000		110,000		25,000
Line of Credit Facility, Remaining Borrowing Capacity									800		800		9,900
Line of Credit Facility, Advance Rate					67.50%
Line of Credit Facility, Change in Maximum Borrowing Capacity	$ 100,000
Long-Term Line of Credit									$ 90,000		$ 90,000		$ 75,000
Line of Credit Facility, Interest Rate at Period End									7.21%		7.21%		7.38%
Restricted Investments									$ 1,100		$ 1,100		$ 1,000
Long-Term Debt, Gross									90,000		90,000		75,000
Debt Instrument, Face Amount									200,000		200,000		100,000
Nuveen Facility [Member] | Selected Interest Rates (Daily) [Member]
Debt Instrument, Basis Spread on Variable Rate	2.95%				3.15%
Asset-backed Notes 2022 [Member]
Debt Instrument, Interest Rate, Stated Percentage																7.56%
Restricted Investments									800		800		1,000
Long-Term Debt, Gross									34,169		34,169		81,078
Debt Instrument, Face Amount									34,169		34,169		81,078			$ 157,800
The 2026 Notes [Member]
Debt Instrument, Interest Rate, Stated Percentage																		4.875%
Long-Term Debt, Gross									57,500		57,500		57,500
Debt Instrument, Face Amount									57,500		57,500		57,500					$ 57,500
The 2026 Notes Underwriter Option [Member]
Debt Instrument, Face Amount																		$ 7,500
Debt Instrument, Convertible, Conversion Price (in dollars per share) | $ / shares																		$ 25
The 2027 Notes [Member]
Debt Instrument, Interest Rate, Stated Percentage																	6.25%
Long-Term Debt, Gross									57,500		57,500		57,500
Debt Instrument, Face Amount									57,500		57,500		57,500				$ 50,000
The 2027 Notes Underwriter Option [Member]
Debt Instrument, Face Amount																	$ 7,500
Debt Instrument, Convertible, Conversion Price (in dollars per share) | $ / shares																	$ 25
The 2031 Convertible Notes [Member]
Debt Instrument, Interest Rate, Stated Percentage				7.125%
Long-Term Debt, Gross									7,500		7,500		20,000
Debt Instrument, Face Amount				$ 20,000					$ 7,500		$ 7,500		$ 20,000
Debt Instrument, Convertible, Conversion Price (in dollars per share) | $ / shares									$ 7.57		$ 7.57
Proceeds from Convertible Debt				$ 18,600
Debt Instrument, Maturity Date				Oct. 17, 2031
Debt Instrument, Interest Rate, Increase From Failure to Maintain Investment Rating				1.00%
Debt Instrument, Interest Rate, Increase From Default				2.00%
Debt Instrument, Redemption Price, Percentage			100.00%	100.00%
Debt Instrument, Convertible, Threshold Consecutive Trading Days											5		5
Debt Instrument, Convertible, Number of Equity Instruments											990,753
Convertible Debt									$ 7,500	$ 0	$ 7,500	$ 0	$ 20,000
Minimum [Member]
Asset Coverage to Borrowings, Ratio, Percent											150.00%
Minimum [Member] | Key Facility [Member] | Prime Rate [Member]
Debt Instrument, Basis Spread on Variable Rate						4.10%	4.25%
Minimum [Member] | Nuveen Facility [Member]
Debt Instrument, Interest Rate, Stated Percentage	5.00%				5.00%
Minimum [Member] | Nuveen Facility [Member] | Selected Interest Rates (Daily) [Member]
Debt Instrument, Basis Spread on Variable Rate, Treasury Yield Maturity (Year)					3 years
Maximum [Member] | Nuveen Facility [Member] | Selected Interest Rates (Daily) [Member]
Debt Instrument, Basis Spread on Variable Rate, Treasury Yield Maturity (Year)					5 years
Weighted Average [Member] | Nuveen Facility [Member] | Selected Interest Rates (Daily) [Member]
Debt Instrument, Basis Spread on Variable Rate, Treasury Yield Maturity (Year)					4 years 10 months 17 days

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