BORROWINGS - Schedule of Borrowings Outstanding (Details) - USD ($) $ in Thousands	Jun. 30, 2024	Mar. 31, 2024
Debt Instrument [Line Items]
Outstanding Balance	$ 743,875	$ 779,875
Unamortized Debt Issuance Costs and Debt Discount/Premium	(8,434)	(9,022)
Recorded Value	735,441	770,853
Estimated Fair Value	687,645	726,298
Line of Credit | Corporate Credit Facility
Debt Instrument [Line Items]
Recorded Value	165,000
SBA Debentures
Debt Instrument [Line Items]
Unamortized Debt Issuance Costs and Debt Discount/Premium	(4,120)	(4,305)
SBA Debentures | Unsecured Debt
Debt Instrument [Line Items]
Outstanding Balance	153,000	153,000
Unamortized Debt Issuance Costs and Debt Discount/Premium	(4,120)	(4,305)
Recorded Value	148,880	148,695
Estimated Fair Value	140,290	141,638
Corporate Credit Facility | Line of Credit
Debt Instrument [Line Items]
Outstanding Balance	165,000
Corporate Credit Facility | Line of Credit | Corporate Credit Facility
Debt Instrument [Line Items]
Outstanding Balance	165,000	265,000
Unamortized Debt Issuance Costs and Debt Discount/Premium	0	0
Recorded Value	165,000	265,000
Estimated Fair Value	165,000	265,000
SPV Credit Facility | Line of Credit | Secured Debt
Debt Instrument [Line Items]
Outstanding Balance	64,000	0
Unamortized Debt Issuance Costs and Debt Discount/Premium	0	0
Recorded Value	64,000	0
Estimated Fair Value	64,000	0
January 2026 Notes
Debt Instrument [Line Items]
Unamortized Debt Issuance Costs and Debt Discount/Premium	(528)	(612)
January 2026 Notes | Notes
Debt Instrument [Line Items]
Outstanding Balance	140,000	140,000
Unamortized Debt Issuance Costs and Debt Discount/Premium	(528)	(612)
Recorded Value	139,472	139,388
Estimated Fair Value	117,213	118,249
October 2026 Notes
Debt Instrument [Line Items]
Unamortized Debt Issuance Costs and Debt Discount/Premium	(1,731)	(1,923)
October 2026 Notes | Notes
Debt Instrument [Line Items]
Outstanding Balance	150,000	150,000
Unamortized Debt Issuance Costs and Debt Discount/Premium	(1,731)	(1,923)
Recorded Value	148,269	148,077
Estimated Fair Value	126,823	127,150
August 2028 Notes
Debt Instrument [Line Items]
Unamortized Debt Issuance Costs and Debt Discount/Premium	(2,055)	(2,182)
August 2028 Notes | Notes
Debt Instrument [Line Items]
Outstanding Balance	71,875	71,875
Unamortized Debt Issuance Costs and Debt Discount/Premium	(2,055)	(2,182)
Recorded Value	69,820	69,693
Estimated Fair Value	$ 74,319	$ 74,261