INCOME TAXES - Net Assets Resulting From Operations To Estimated RIC Taxable Income (Details) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Mar. 31, 2024	Dec. 31, 2023	Sep. 30, 2023	Jun. 30, 2023	Mar. 31, 2023	Dec. 31, 2022	Sep. 30, 2022	Jun. 30, 2022	Mar. 31, 2024	Mar. 31, 2023	Mar. 31, 2022
Income Tax Disclosure [Abstract]
Net increase in net assets from operations	$ 13,469	$ 23,484	$ 22,624	$ 23,812	$ 18,176	$ 2,949	$ 9,458	$ 2,510	$ 83,389	$ 33,093	$ 42,815
Net unrealized (appreciation) depreciation on investments									(13,640)	18,589	(11,467)
(Expense/loss) income/gain recognized for tax on pass-through entities									(6,383)	962	3,753
Loss (gain) recognized on dispositions									16,074	(1,473)	152
Capital loss carryover									26,449	12,796	(878)
Net operating (income) loss - wholly-owned subsidiary									(5,194)	809	(10,757)
Dividend income from wholly-owned subsidiary									2,000	1,068	4,000
Non-deductible tax expense									921	628	65
Loss on extinguishment of debt									(2,726)	(2,726)	12,268
Non-deductible compensation									3,665	3,243	3,679
Compensation related book/tax differences									1,116	812	36
Interest on non-accrual loans									5,636	3,343	4,171
Other book/tax differences									4,403	1,191	1,530
Estimated distributable income before deductions for distributions									115,710	72,335	49,367
Ordinary									101,517	70,034	57,518
Estimated annual RIC undistributed taxable income									14,193	$ 2,301	$ (8,151)
Capital loss carryover	$ 60,100								$ 60,100