SENIOR SECURITIES (Details) - USD ($) $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2025	Sep. 20, 2017
SBA-guaranteed debentures Fiscal 2016
Notes
Outstanding Exclusive of Treasury Securities	$ 65,000
SBA-guaranteed debentures Fiscal 2017
Notes
Outstanding Exclusive of Treasury Securities	90,000
SBA-guaranteed debentures Fiscal 2018
Notes
Outstanding Exclusive of Treasury Securities	150,000
SBA-guaranteed debentures Fiscal 2019
Notes
Outstanding Exclusive of Treasury Securities	161,000
SBA-guaranteed debentures Fiscal 2020
Notes
Outstanding Exclusive of Treasury Securities	176,500
SBA-guaranteed debentures Fiscal 2021
Notes
Outstanding Exclusive of Treasury Securities	250,000
SBA-guaranteed debentures Fiscal 2022
Notes
Outstanding Exclusive of Treasury Securities	313,600
SBA-guaranteed debentures Fiscal 2023
Notes
Outstanding Exclusive of Treasury Securities	325,000
SBA-guaranteed debentures Fiscal 2024
Notes
Outstanding Exclusive of Treasury Securities	325,000
SBA-Guaranteed Debentures Fiscal 2025
Notes
Outstanding Exclusive of Treasury Securities	299,000
Original Credit Facility Fiscal 2015
Notes
Outstanding Exclusive of Treasury Securities	$ 109,500
Asset Coverage per Unit	$ 2,220
Original Credit Facility Fiscal 2016
Notes
Outstanding Exclusive of Treasury Securities	$ 116,000
Asset Coverage per Unit	$ 2,210
Credit Facility Fiscal 2017
Notes
Outstanding Exclusive of Treasury Securities	$ 40,750
Asset Coverage per Unit	$ 3,460
Credit Facility Fiscal 2018
Notes
Outstanding Exclusive of Treasury Securities	$ 99,550
Asset Coverage per Unit	$ 2,520
Credit Facility Fiscal 2019
Notes
Outstanding Exclusive of Treasury Securities	$ 161,550
Asset Coverage per Unit	$ 2,286
Credit Facility Fiscal 2020
Notes
Outstanding Exclusive of Treasury Securities	$ 174,000
Asset Coverage per Unit	$ 2,230
Credit Facility Fiscal 2021
Notes
Outstanding Exclusive of Treasury Securities	$ 177,340
Asset Coverage per Unit	$ 2,030
Credit Facility Fiscal 2022
Notes
Outstanding Exclusive of Treasury Securities	$ 199,200
Asset Coverage per Unit	$ 1,920
Credit Facility Fiscal 2023
Notes
Outstanding Exclusive of Treasury Securities	$ 160,086
Asset Coverage per Unit	$ 2,230
Credit Facility Fiscal 2024
Notes
Outstanding Exclusive of Treasury Securities	$ 175,386
Asset Coverage per Unit	$ 2,340
Credit Facility Fiscal 2025
Notes
Outstanding Exclusive of Treasury Securities	$ 236,649
Asset Coverage per Unit	$ 2,030
Notes 2030 Fiscal 2025
Notes
Outstanding Exclusive of Treasury Securities	$ 125,000
Asset Coverage per Unit	$ 2,030
Notes 2026 Fiscal 2021
Notes
Outstanding Exclusive of Treasury Securities	$ 100,000
Asset Coverage per Unit	$ 2,030
Notes 2026 Fiscal 2022
Notes
Outstanding Exclusive of Treasury Securities	$ 100,000
Asset Coverage per Unit	$ 1,920
Notes 2026 Fiscal 2023
Notes
Outstanding Exclusive of Treasury Securities	$ 100,000
Asset Coverage per Unit	$ 2,230
Notes 2026 Fiscal 2024
Notes
Outstanding Exclusive of Treasury Securities	$ 100,000
Asset Coverage per Unit	$ 2,340
Notes 2022 Fiscal 2017
Notes
Outstanding Exclusive of Treasury Securities	$ 48,875
Asset Coverage per Unit	$ 3,460
Average Market Value per Unit	$ 25.34
Notes 2022 Fiscal 2018
Notes
Outstanding Exclusive of Treasury Securities	$ 48,875
Asset Coverage per Unit	$ 2,520
Average Market Value per Unit	$ 25.18
Notes 2022 Fiscal 2019
Notes
Outstanding Exclusive of Treasury Securities	$ 48,875
Asset Coverage per Unit	$ 2,286
Average Market Value per Unit	$ 24.43
Notes 2022 Fiscal 2020
Notes
Outstanding Exclusive of Treasury Securities	$ 48,875
Asset Coverage per Unit	$ 2,230
Average Market Value per Unit	$ 23.64
6.50% Notes due 2019
Notes
Notes interest rate	6.50%	6.50%
6.50% Notes due 2019, Fiscal 2016
Notes
Outstanding Exclusive of Treasury Securities	$ 25,000
Asset Coverage per Unit	$ 2,210
Average Market Value per Unit	$ 25.11