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Note 7 - Borrowings (Details Textual) - USD ($) $ / shares in Units, $ in Thousands						12 Months Ended				24 Months Ended	21840 Months Ended
		Feb. 25, 2022	Jun. 22, 2021	Apr. 24, 2021	Apr. 21, 2020	Dec. 31, 2022		Dec. 31, 2021	Dec. 31, 2020	Jun. 04, 2020	Feb. 25, 2022	Nov. 09, 2022	Jun. 15, 2022	Mar. 30, 2021	Dec. 31, 2019	Sep. 15, 2019	Aug. 13, 2019	Jun. 19, 2019	Dec. 31, 2018	Jun. 01, 2018	Oct. 11, 2017	Sep. 29, 2017
Asset Coverage to Borrowings, Ratio, Percent						172.00%
Restricted Investments						$ 2,788		$ 1,359
Long-Term Debt, Gross	[1]					439,323		260,250	$ 187,625						$ 154,375				$ 127,875
Debt Instrument, Face Amount						582,573		353,000
Interest Paid, Excluding Capitalized Interest, Operating Activities						17,028		10,706	8,593
Reserve Cash Balance [Member]
Restricted Investments						$ 1,000		$ 500
Key Facility [Member]
Line of Credit Facility, Maximum Borrowing Capacity, Accordian Feature			$ 150,000
Line of Credit Facility, Maximum Borrowing Capacity			$ 125,000
Line of Credit Facility, Advance Rate of Eligible Debt Investments			60.00%
Long-Term Debt, Weighted Average Interest Rate, over Time						5.33%		4.25%
Line of Credit Facility, Unused Capacity, Commitment Fee Percentage						0.50%
Line of Credit Facility, Current Borrowing Capacity						$ 120,000		$ 71,500
Line of Credit Facility, Remaining Borrowing Capacity						40,200		19,800
Long-Term Debt, Gross						5,000		53,500
Debt Instrument, Face Amount						$ 125,000		$ 125,000
Key Facility [Member] | London Interbank Offered Rate (LIBOR) [Member]
Debt Instrument, Basis Spread on Variable Rate			3.25%
Key Facility [Member] | Prime Rate [Member]
Debt Instrument, Basis Spread on Variable Rate						0.25%
Debt Instrument, Variable Rate						7.50%		3.25%
NYL Facility [Member]
Line of Credit Facility, Maximum Borrowing Capacity		$ 200,000			$ 100,000						$ 200,000									$ 100,000
Line of Credit Facility, Current Borrowing Capacity						$ 23,200		$ 21,200
Line of Credit Facility, Remaining Borrowing Capacity						23,200		5,700
Line of Credit Facility, Maximum Borrowing Capacity, Accordion Feature					$ 200,000															$ 200,000
Line of Credit Facility, Advance Rate					67.00%													67.00%
Line of Credit Facility, Change in Maximum Borrowing Capacity		$ 100,000
Long-Term Line of Credit, Total						$ 176,800		$ 78,800
Line of Credit Facility, Interest Rate at Period End						5.57%		4.62%
Long-Term Debt, Gross						$ 176,750		$ 78,750
Debt Instrument, Face Amount						200,000		100,000
NYL Facility [Member] | USD Mid-market Wwap Rate [Member]
Debt Instrument, Basis Spread on Variable Rate											3.00%
Asset-backed Notes 2019 [Member]
Restricted Investments						600		900
Debt Instrument, Interest Rate, Stated Percentage																	4.21%
Long-Term Debt, Gross						42,600		70,500
Debt Instrument, Face Amount																	$ 160,000
Asset-backed Notes 2022 [Member]
Restricted Investments						1,000
Debt Instrument, Interest Rate, Stated Percentage												7.56%
Long-Term Debt, Gross						100,000		0
Debt Instrument, Face Amount						100,000		0				$ 157,800
The 6.25 % Notes Due 2022 [Member]
Debt Instrument, Interest Rate, Stated Percentage																						6.25%
Debt Instrument, Face Amount																						$ 32,500
Adittional 2022 Notes [Member]
Debt Instrument, Face Amount																					$ 4,900
The 2022 Notes [Member]
Debt Instrument, Interest Rate, Stated Percentage																6.25%
Long-Term Debt, Gross	[1]					0		0	$ 37,375						$ 37,375				$ 37,375
Debt Instrument, Convertible, Conversion Price (in dollars per share)																$ 25
Repayments of Debt				$ 37,400
Interest Paid, Excluding Capitalized Interest, Operating Activities				300
Payments of Debt Issuance Costs				$ 400
The 2026 Notes [Member]
Debt Instrument, Interest Rate, Stated Percentage														4.875%
Long-Term Debt, Gross	[1]					57,500		57,500
Debt Instrument, Face Amount						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)														$ 25
The 2027 Notes [Member]
Debt Instrument, Interest Rate, Stated Percentage													6.25%
Long-Term Debt, Gross						57,500	[1]	0
Debt Instrument, Face Amount						$ 57,500		$ 0					$ 50,000
The 2027 Notes Underwriter Option [Member]
Debt Instrument, Face Amount													$ 7,500
Debt Instrument, Convertible, Conversion Price (in dollars per share)													$ 25
Minimum [Member]
Asset Coverage to Borrowings, Ratio, Percent						150.00%
Minimum [Member] | Key Facility [Member] | London Interbank Offered Rate (LIBOR) [Member]
Debt Instrument, Basis Spread on Variable Rate			1.00%
Minimum [Member] | Key Facility [Member] | Prime Rate [Member]
Debt Instrument, Basis Spread on Variable Rate						4.25%
Minimum [Member] | NYL Facility [Member] | USD Mid-market Wwap Rate [Member]
Debt Instrument, Basis Spread on Variable Rate					3.55%					2.75%
Maximum [Member] | NYL Facility [Member] | USD Mid-market Wwap Rate [Member]
Debt Instrument, Basis Spread on Variable Rate					5.15%					3.25%
[1] Total amount of senior securities outstanding at the end of the period presented.

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Amount, before unamortized (discount) premium and debt issuance costs, of long-term debt. Includes, but is not limited to, notes payable, bonds payable, commercial loans, mortgage loans, convertible debt, subordinated debt and other types of debt.

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The price per share of the conversion feature embedded in the debt instrument.

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Face (par) amount of debt instrument at time of issuance.

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Contractual interest rate for funds borrowed, under the debt agreement.

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Amount of cash paid for interest, excluding capitalized interest, classified as operating activity. Includes, but is not limited to, payment to settle zero-coupon bond for accreted interest of debt discount and debt instrument with insignificant coupon interest rate in relation to effective interest rate of borrowing attributable to accreted interest of debt discount.

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Amount of current borrowing capacity under the credit facility considering any current restrictions on the amount that could be borrowed (for example, borrowings may be limited by the amount of current assets), but without considering any amounts currently outstanding under the facility.

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Maximum borrowing capacity under the credit facility without consideration of any current restrictions on the amount that could be borrowed or the amounts currently outstanding under the facility.

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Amount of borrowing capacity currently available under the credit facility (current borrowing capacity less the amount of borrowings outstanding).

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The fee, expressed as a percentage of the line of credit facility, for available but unused credit capacity under the credit facility.

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Weighted average interest rate of long-term debt outstanding calculated over time.

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