BORROWINGS - Schedule of Borrowings Outstanding (Details) - USD ($) $ in Thousands	Mar. 31, 2024	Mar. 31, 2023
Debt Instrument [Line Items]
Outstanding Balance	$ 779,875	$ 645,000
Unamortized Debt Issuance Costs and Debt Discount/Premium	(9,022)	(7,356)
Recorded Value	770,853	637,644
Estimated Fair Value	726,298	605,842
Line of Credit | Corporate Credit Facility
Debt Instrument [Line Items]
Recorded Value	265,000
SBA Debentures
Debt Instrument [Line Items]
Unamortized Debt Issuance Costs and Debt Discount/Premium	(4,305)	(3,670)
SBA Debentures | Unsecured Debt
Debt Instrument [Line Items]
Outstanding Balance	153,000	120,000
Unamortized Debt Issuance Costs and Debt Discount/Premium	(4,305)	(3,670)
Recorded Value	148,695	116,330
Estimated Fair Value	141,638	115,836
Corporate Credit Facility | Line of Credit
Debt Instrument [Line Items]
Outstanding Balance	265,000
Corporate Credit Facility | Line of Credit | Corporate Credit Facility
Debt Instrument [Line Items]
Outstanding Balance	265,000	235,000
Unamortized Debt Issuance Costs and Debt Discount/Premium	0	0
Recorded Value	265,000	235,000
Estimated Fair Value	265,000	235,000
SPV Credit Facility | Line of Credit | Secured Debt
Debt Instrument [Line Items]
Outstanding Balance	0
Unamortized Debt Issuance Costs and Debt Discount/Premium	0
Recorded Value	0
Estimated Fair Value	0
January 2026 Notes
Debt Instrument [Line Items]
Unamortized Debt Issuance Costs and Debt Discount/Premium	(612)	(949)
January 2026 Notes | Notes
Debt Instrument [Line Items]
Outstanding Balance	140,000	140,000
Unamortized Debt Issuance Costs and Debt Discount/Premium	(612)	(949)
Recorded Value	139,388	139,051
Estimated Fair Value	118,249	122,768
October 2026 Notes
Debt Instrument [Line Items]
Unamortized Debt Issuance Costs and Debt Discount/Premium	(1,923)	(2,737)
October 2026 Notes | Notes
Debt Instrument [Line Items]
Outstanding Balance	150,000	150,000
Unamortized Debt Issuance Costs and Debt Discount/Premium	(1,923)	(2,737)
Recorded Value	148,077	147,263
Estimated Fair Value	127,150	132,238
August 2028 Notes
Debt Instrument [Line Items]
Unamortized Debt Issuance Costs and Debt Discount/Premium	(2,182)	$ 0
August 2028 Notes | Notes
Debt Instrument [Line Items]
Outstanding Balance	71,875
Unamortized Debt Issuance Costs and Debt Discount/Premium	(2,182)
Recorded Value	69,693
Estimated Fair Value	$ 74,261