Note 7 - Borrowings - Borrowings (Details) - USD ($) $ in Thousands	Mar. 31, 2026	Dec. 31, 2025	Dec. 15, 2025	Sep. 04, 2025	Oct. 17, 2024	Jun. 15, 2022	Mar. 30, 2021
Total commitment	$ 734,200	$ 806,750
Balance outstanding	450,200	477,750
Unused commitment	284,000	329,000
Unamortized debt issuance costs attributable to term borrowings	(3,034)	(4,723)
Total borrowings outstanding, net	447,166	473,027
Key Facility [Member]
Total commitment	150,000	150,000
Balance outstanding	45,000	0
Unused commitment	105,000	150,000
NYL Facility [Member]
Total commitment	250,000	250,000
Balance outstanding	181,000	181,000
Unused commitment	69,000	69,000
Nuveen Facility [Member]
Total commitment	200,000	200,000
Balance outstanding	90,000	90,000
Unused commitment	110,000	110,000
The 2028 Notes [Member]
Total commitment	57,500	57,500	$ 57,500
Balance outstanding	57,500	57,500
Unused commitment	0	0
The 2027 Notes [Member]
Total commitment	57,500	57,500				$ 50,000
Balance outstanding	57,500	57,500
Unused commitment	0	0
The 2026 Notes [Member]
Total commitment	0	57,500					$ 57,500
Balance outstanding	0	57,500
Unused commitment	0	0
The 2030 Convertible Notes [Member]
Total commitment	16,450	31,500		$ 40,000
Balance outstanding	16,450	31,500
Unused commitment	0	0
The 2031 Convertible Notes [Member]
Total commitment	2,750	2,750			$ 20,000
Balance outstanding	2,750	2,750
Unused commitment	$ 0	$ 0