FAIR VALUE MEASUREMENTS - Schedule Investment Portfolio by Level (Details) - USD ($) $ in Thousands	9 Months Ended
	Dec. 31, 2022		Mar. 31, 2022
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Total Investments	$ 1,150,046	[1],[2],[3]	$ 936,614	[4],[5],[6]
Significant Unobservable Inputs (Level 3)
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Total Investments	1,102,421
Total Investments			879,011
Recurring
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Total Investments	1,150,046		936,614
Recurring | Quoted Prices in Active Markets for Identical Assets (Level 1)
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Total Investments	0		0
Recurring | Significant Other Observable Inputs (Level 2)
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Total Investments	0		0
Recurring | Significant Unobservable Inputs (Level 3)
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Total Investments	1,102,421		879,011
Recurring | Net Asset Value
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Investments measured at net asset value	$ 47,625		57,603
Prior notice period to sell or transfer membership interest	60 days
Recurring | First lien loans
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Total Investments	$ 954,000		739,872
Recurring | First lien loans | Quoted Prices in Active Markets for Identical Assets (Level 1)
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Total Investments	0		0
Recurring | First lien loans | Significant Other Observable Inputs (Level 2)
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Total Investments	0		0
Recurring | First lien loans | Significant Unobservable Inputs (Level 3)
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Total Investments	954,000		739,872
Recurring | Second lien loans
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Total Investments	35,446		52,645
Recurring | Second lien loans | Quoted Prices in Active Markets for Identical Assets (Level 1)
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Total Investments	0		0
Recurring | Second lien loans | Significant Other Observable Inputs (Level 2)
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Total Investments	0		0
Recurring | Second lien loans | Significant Unobservable Inputs (Level 3)
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Total Investments	35,446		52,645
Recurring | Subordinated debt
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Total Investments	852		1,317
Recurring | Subordinated debt | Quoted Prices in Active Markets for Identical Assets (Level 1)
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Total Investments	0		0
Recurring | Subordinated debt | Significant Other Observable Inputs (Level 2)
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Total Investments	0		0
Recurring | Subordinated debt | Significant Unobservable Inputs (Level 3)
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Total Investments	852		1,317
Recurring | Preferred equity
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Total Investments	61,283		44,663
Recurring | Preferred equity | Quoted Prices in Active Markets for Identical Assets (Level 1)
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Total Investments	0		0
Recurring | Preferred equity | Significant Other Observable Inputs (Level 2)
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Total Investments	0		0
Recurring | Preferred equity | Significant Unobservable Inputs (Level 3)
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Total Investments	61,283		44,663
Recurring | Common equity & warrants
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Total Investments	50,840		40,514
Recurring | Common equity & warrants | Quoted Prices in Active Markets for Identical Assets (Level 1)
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Total Investments	0		0
Recurring | Common equity & warrants | Significant Other Observable Inputs (Level 2)
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Total Investments	0		0
Recurring | Common equity & warrants | Significant Unobservable Inputs (Level 3)
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Total Investments	$ 50,840		$ 40,514

[1] All debt investments are income-producing, unless otherwise noted. Equity investments are non-income producing, unless otherwise noted.

[2] Equity ownership may be held in shares or units of a company that is either wholly owned by the portfolio company or under common control by the same parent company to the portfolio company.

[3] The Company's investment portfolio is comprised entirely of debt and equity securities of privately held companies for which quoted prices falling within the categories of Level 1 and Level 2 inputs are not readily available. Therefore, the Company values all of its portfolio investments at fair value, as determined in good faith by the Board of Directors, using significant unobservable Level 3 inputs. Refer to Note 4 - Fair Value Measurements for further discussion.

[4] All debt investments are income-producing, unless otherwise noted. Equity investments and warrants are non-income producing, unless otherwise noted.

[5] Equity ownership may be held in shares or units of a company that is either wholly owned by the portfolio company or under common control by the same parent company to the portfolio company.

[6] The Company's investment portfolio is comprised entirely of debt and equity securities of privately held companies for which quoted prices falling within the categories of Level 1 and Level 2 inputs are not readily available. Therefore, the Company values all of its portfolio investments at fair value, as determined in good faith by the Board of Directors, using significant unobservable Level 3 inputs. Refer to Note 4 for further discussion.