FAIR VALUE MEASUREMENTS - Schedule Investment Portfolio by Level (Details) - USD ($) $ in Thousands	3 Months Ended
	Jun. 30, 2023		Mar. 31, 2023
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Investment owned, fair value	$ 1,285,318	[1],[2],[3]	$ 1,206,388	[4],[5],[6]
Significant Unobservable Inputs (Level 3)
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Investment owned, fair value	1,233,456
Total Investments			1,155,132
Recurring
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Total Investments	1,285,318		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	1,233,456		1,155,132
Recurring | Net Asset Value
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Investments measured at net asset value	$ 51,862		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	$ 1,075,200		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	1,075,200		1,000,984
Recurring | Second lien loans
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Investment owned, fair value	34,935		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	34,935		35,820
Recurring | Subordinated debt
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Investment owned, fair value	780		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	780		791
Recurring | Preferred equity
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Investment owned, fair value	67,659		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	67,659		63,393
Recurring | Common equity & warrants
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Investment owned, fair value	54,882		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	$ 54,882		$ 54,144

[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 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 1940 Act, 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 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 - Fair Value Measurements to our audited consolidated financial statements for further discussion.