FAIR VALUE MEASUREMENTS - Changes in Fair Value of Investments Measured Using Level 3 Inputs (Details) - USD ($) $ in Thousands	12 Months Ended
	Mar. 31, 2025	Mar. 31, 2024
First lien loans
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Fair value, beginning balance	$ 1,309,449	$ 1,000,984
Realized & Unrealized Gains (Losses)	(61,142)	(25,020)
Purchases of Investments	616,629	520,239
Repayments	(244,854)	(176,763)
PIK Interest Capitalized	12,843	10,845
Divestitures	(31,584)	(13,875)
Conversion/Exchange of Security	(14,719)	(6,961)
Fair value. ending balance	1,586,622	1,309,449
YTD Unrealized Appreciation (Depreciation) on Investments held at period end	(21,908)	(19,824)
Second lien loans
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Fair value, beginning balance	33,774	35,820
Realized & Unrealized Gains (Losses)	(6,960)	342
Purchases of Investments	37	169
Repayments	(3,840)	(2,913)
PIK Interest Capitalized	70	356
Divestitures	0	0
Conversion/Exchange of Security	(5,015)	0
Fair value. ending balance	18,066	33,774
YTD Unrealized Appreciation (Depreciation) on Investments held at period end	(5,062)	339
Subordinated debt
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Fair value, beginning balance	1,336	791
Realized & Unrealized Gains (Losses)	36	(31)
Purchases of Investments	57	562
Repayments	(75)	(19)
PIK Interest Capitalized	17	33
Divestitures	0	0
Conversion/Exchange of Security	(153)	0
Fair value. ending balance	1,218	1,336
YTD Unrealized Appreciation (Depreciation) on Investments held at period end	28	(31)
Preferred equity
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Fair value, beginning balance	71,127	63,393
Realized & Unrealized Gains (Losses)	25,094	(5,442)
Purchases of Investments	9,767	10,279
Repayments	0	0
PIK Interest Capitalized	0	0
Divestitures	(16,920)	(273)
Conversion/Exchange of Security	13,850	3,170
Fair value. ending balance	102,918	71,127
YTD Unrealized Appreciation (Depreciation) on Investments held at period end	18,671	(5,340)
Common equity & warrants
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Fair value, beginning balance	60,875	54,144
Realized & Unrealized Gains (Losses)	3,593	517
Purchases of Investments	7,036	6,281
Repayments	0	0
PIK Interest Capitalized	0	0
Divestitures	(1,066)	(3,858)
Conversion/Exchange of Security	6,037	3,791
Fair value. ending balance	76,475	60,875
YTD Unrealized Appreciation (Depreciation) on Investments held at period end	4,388	285
Total Investments
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Fair value, beginning balance	1,476,561	1,155,132
Realized & Unrealized Gains (Losses)	(39,379)	(29,634)
Purchases of Investments	633,526	537,530
Repayments	(248,769)	(179,695)
PIK Interest Capitalized	12,930	11,234
Divestitures	(49,570)	(18,006)
Conversion/Exchange of Security	0	0
Fair value. ending balance	1,785,299	1,476,561
YTD Unrealized Appreciation (Depreciation) on Investments held at period end	(3,883)	$ (24,571)
Cost basis allocated from first lien debt to warrants
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Conversion/Exchange of Security	$ 3,800