FAIR VALUE MEASUREMENTS - Schedule Investment Portfolio by Level (Details) - USD ($) $ in Thousands	9 Months Ended
	Dec. 31, 2023		Mar. 31, 2023
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Investment owned, fair value	$ 1,365,037	[1],[2],[3],[4],[5],[6],[7]	$ 1,206,388	[8],[9],[10]
Significant Unobservable Inputs (Level 3)
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Investment owned, fair value	1,310,837
Total Investments			1,155,132
Recurring
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Total Investments	1,365,037		1,206,388
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	1,310,837		1,155,132
Recurring | Net Asset Value
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Investments measured at net asset value	$ 54,200		51,256
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]
Investment owned, fair value	$ 1,146,355		1,000,984
Recurring | First lien loans | Quoted Prices in Active Markets for Identical Assets (Level 1)
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Investment owned, fair value	0		0
Recurring | First lien loans | Significant Other Observable Inputs (Level 2)
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Investment owned, fair value	0		0
Recurring | First lien loans | Significant Unobservable Inputs (Level 3)
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Investment owned, fair value	1,146,355		1,000,984
Recurring | Second lien loans
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Investment owned, fair value	34,614		35,820
Recurring | Second lien loans | Quoted Prices in Active Markets for Identical Assets (Level 1)
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Investment owned, fair value	0		0
Recurring | Second lien loans | Significant Other Observable Inputs (Level 2)
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Investment owned, fair value	0		0
Recurring | Second lien loans | Significant Unobservable Inputs (Level 3)
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Investment owned, fair value	34,614		35,820
Recurring | Subordinated debt
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Investment owned, fair value	768		791
Recurring | Subordinated debt | Quoted Prices in Active Markets for Identical Assets (Level 1)
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Investment owned, fair value	0		0
Recurring | Subordinated debt | Significant Other Observable Inputs (Level 2)
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Investment owned, fair value	0		0
Recurring | Subordinated debt | Significant Unobservable Inputs (Level 3)
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Investment owned, fair value	768		791
Recurring | Preferred equity
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Investment owned, fair value	68,644		63,393
Recurring | Preferred equity | Quoted Prices in Active Markets for Identical Assets (Level 1)
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Investment owned, fair value	0		0
Recurring | Preferred equity | Significant Other Observable Inputs (Level 2)
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Investment owned, fair value	0		0
Recurring | Preferred equity | Significant Unobservable Inputs (Level 3)
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Investment owned, fair value	68,644		63,393
Recurring | Common equity & warrants
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Investment owned, fair value	60,456		54,144
Recurring | Common equity & warrants | Quoted Prices in Active Markets for Identical Assets (Level 1)
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Investment owned, fair value	0		0
Recurring | Common equity & warrants | Significant Other Observable Inputs (Level 2)
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Investment owned, fair value	0		0
Recurring | Common equity & warrants | Significant Unobservable Inputs (Level 3)
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Investment owned, fair value	$ 60,456		$ 54,144

[1] All portfolio company headquarters are based in the United States, 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] Non-Control/Non-Affiliate investments are generally defined by the 1940 Act, as investments that are neither control investments nor affiliate investments. At December 31, 2023, the Company held $1,124.9 million of non-control/non-affiliate investments, which represented approximately 82.4% of the Company’s investment assets. The fair value of these investments as a percent of net assets is 156.0%.

[4] Affiliate investments are generally defined by the 1940 Act as investments in which between 5% and 25% of the voting securities are owned and the investments are not classified as control investments. At December 31, 2023, the Company held $186.0 million of affiliate investments, which represented approximately 13.6% of the Company’s investment assets. The fair value of these investments as a percent of net assets is 25.8%.

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

[6] Control investments are generally defined by the 1940 Act as investments in which more than 25% of the voting securities are owned. At December 31, 2023, the Company held $54.2 million of control investments, which represented approximately 4.0% of the Company’s investment assets were . The fair value of these investments as a percent of net assets is 7.5%.

[7] 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 valuation committee comprised of certain officers of the Company (the "Valuation Committee") as the valuation designee of the Board of Directors (the "Valuation Designee") pursuant to Rule 2a-5 under the Investment Company Act of 1940, as amended (the “1940 Act”), using significant unobservable Level 3 inputs. Refer to Note 4 - Fair Value Measurements for further discussion.

[8] 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.

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

[10] 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 to our audited consolidated financial statements for further discussion.