FAIR VALUE MEASUREMENTS - Changes in Fair Value of Investments Measured Using Level 3 Inputs (Details) - USD ($) $ in Thousands	6 Months Ended
	Sep. 30, 2025	Sep. 30, 2024
Total Investments
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Fair value, beginning balance	$ 1,785,299	$ 1,476,561
Realized & Unrealized Gains (Losses)	(6,686)	(22,862)
Purchases of Investments	245,933	203,549
Repayments	(116,483)	(132,221)
PIK Interest Capitalized	6,115	6,065
Divestitures	(36,271)	(22,585)
Conversion/Exchange of Security	0	0
Fair value. ending balance	1,877,907	1,508,507
YTD Unrealized Appreciation (Depreciation) on Investments held at period end	379	(21,249)
First lien loans
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Fair value, beginning balance	1,586,622	1,309,449
Realized & Unrealized Gains (Losses)	(19,113)	(14,912)
Purchases of Investments	236,403	196,254
Repayments	(116,337)	(128,801)
PIK Interest Capitalized	6,107	5,984
Divestitures	(1,789)	(22,585)
Conversion/Exchange of Security	(3,951)	0
Fair value. ending balance	1,687,942	1,345,389
YTD Unrealized Appreciation (Depreciation) on Investments held at period end	(16,012)	(15,970)
Second lien loans
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Fair value, beginning balance	18,066	33,774
Realized & Unrealized Gains (Losses)	(922)	(1,986)
Purchases of Investments	26	(4)
Repayments	0	(3,420)
PIK Interest Capitalized	0	70
Divestitures	0	0
Conversion/Exchange of Security	0	(1,062)
Fair value. ending balance	17,170	27,372
YTD Unrealized Appreciation (Depreciation) on Investments held at period end	(922)	(106)
Subordinated debt
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Fair value, beginning balance	1,218	1,336
Realized & Unrealized Gains (Losses)	2	29
Purchases of Investments	57	57
Repayments	(146)	0
PIK Interest Capitalized	8	11
Divestitures	0	0
Conversion/Exchange of Security	0	(153)
Fair value. ending balance	1,139	1,280
YTD Unrealized Appreciation (Depreciation) on Investments held at period end	2	21
Preferred equity
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Fair value, beginning balance	102,918	71,127
Realized & Unrealized Gains (Losses)	(7,860)	(132)
Purchases of Investments	3,427	3,557
Repayments	0	0
PIK Interest Capitalized	0	0
Divestitures	(31,323)	0
Conversion/Exchange of Security	(688)	0
Fair value. ending balance	66,474	74,552
YTD Unrealized Appreciation (Depreciation) on Investments held at period end	(3,475)	(132)
Common equity & warrants
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Fair value, beginning balance	76,475	60,875
Realized & Unrealized Gains (Losses)	20,922	(5,861)
Purchases of Investments	2,563	3,685
Repayments	0	0
PIK Interest Capitalized	0	0
Divestitures	(3,159)	0
Conversion/Exchange of Security	4,639	1,215
Fair value. ending balance	101,440	59,914
YTD Unrealized Appreciation (Depreciation) on Investments held at period end	20,501	$ (5,062)
Earnout
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Fair value, beginning balance	0
Realized & Unrealized Gains (Losses)	285
Purchases of Investments	3,457
Repayments	0
PIK Interest Capitalized	0
Divestitures	0
Conversion/Exchange of Security	0
Fair value. ending balance	3,742
YTD Unrealized Appreciation (Depreciation) on Investments held at period end	$ 285