BORROWINGS - Schedule of Borrowings Outstanding (Details) - USD ($) $ in Thousands	Sep. 30, 2023	Mar. 31, 2023
Debt Instrument [Line Items]
Outstanding Balance	$ 741,875	$ 645,000
Unamortized Debt Issuance Costs and Debt Discount/Premium	(9,208)	(7,356)
Recorded Value	732,667	637,644
Line of Credit | Credit Facility
Debt Instrument [Line Items]
Outstanding Balance	250,000
Unamortized Debt Issuance Costs and Debt Discount/Premium	0
Recorded Value	250,000
SBA Debentures | Unsecured Debt
Debt Instrument [Line Items]
Outstanding Balance	130,000	120,000
Unamortized Debt Issuance Costs and Debt Discount/Premium	(3,624)	(3,670)
Recorded Value	126,376	116,330
Credit Facility | Line of Credit
Debt Instrument [Line Items]
Outstanding Balance		235,000
Unamortized Debt Issuance Costs and Debt Discount/Premium		0
Recorded Value		235,000
January 2026 Notes | Notes
Debt Instrument [Line Items]
Outstanding Balance	140,000	140,000
Unamortized Debt Issuance Costs and Debt Discount/Premium	(780)	(949)
Recorded Value	139,220	139,051
October 2026 Notes | Notes
Debt Instrument [Line Items]
Outstanding Balance	150,000	150,000
Unamortized Debt Issuance Costs and Debt Discount/Premium	(2,367)	(2,737)
Recorded Value	147,633	$ 147,263
August 2028 Notes | Notes
Debt Instrument [Line Items]
Outstanding Balance	71,875
Unamortized Debt Issuance Costs and Debt Discount/Premium	(2,437)
Recorded Value	$ 69,438