SECURED BORROWINGS - Narrative (Details)								3 Months Ended		6 Months Ended		12 Months Ended
	Mar. 14, 2024 USD ($)	Dec. 07, 2023 USD ($)	Nov. 21, 2023 USD ($)	Nov. 20, 2023 USD ($)	Jun. 23, 2023 USD ($)	May 20, 2022 USD ($)	May 05, 2022	Jun. 30, 2024 USD ($)	Jun. 30, 2023 USD ($)	Jun. 30, 2024 USD ($)	Jun. 30, 2023 USD ($)	Dec. 31, 2023 USD ($)	Apr. 09, 2024 USD ($)	Apr. 08, 2024 USD ($)	Dec. 06, 2023 USD ($)	Jun. 30, 2022	Sep. 10, 2020 USD ($)	Dec. 30, 2019 USD ($)
Debt Instrument [Line Items]
Asset Coverage Ratio								195.88%	167.54%	195.88%	167.54%	178.57%
Total Commitment								$ 1,322,000,000		$ 1,322,000,000		$ 1,167,000,000
Amount available								289,990,000		289,990,000		214,960,000
Borrowing interest expense								17,689,000	$ 13,610,000	33,026,000	$ 25,651,000
Unused fees								368,000	239,000	676,000	506,000
Amortization of deferred financing costs								664,000	449,000	1,960,000	884,000
Interest and debt financing expenses								18,721,000	14,298,000	35,662,000	27,041,000
Credit Facility | Secured Debt
Debt Instrument [Line Items]
Total Commitment													$ 250,000,000	$ 185,000,000
Subscription Facility | Credit Facility | Secured Debt
Debt Instrument [Line Items]
Total Commitment																	$ 50,000,000
Borrowing interest expense								0	260,000	0	359,000
Unused fees								0	23,000	0	50,000
Amortization of deferred financing costs								0	42,000	0	84,000
Interest and debt financing expenses								0	325,000	0	493,000
Wells Fargo Financing Facility | Credit Facility | Secured Debt
Debt Instrument [Line Items]
Total Commitment	$ 250,000,000							150,000,000		150,000,000		275,000,000						$ 275,000,000
Amount available	$ 150,000,000							81,000,000		81,000,000		$ 43,837,000
Covenant asset coverage ratio																1.50
Commitment reduction fee, percentage							1.00%
Line of credit facility, unused capacity, commitment fee percentage, less than forty percent of total commitments	0.50%
Line of credit facility, maximum borrowing capacity percentage	40.00%
Line of credit facility, unused capacity, commitment fee percentage, in excess of forty percent of total commitments	1.50%
Borrowing interest expense								758,000	2,636,000	3,813,000	4,719,000
Unused fees								80,000	163,000	176,000	359,000
Amortization of deferred financing costs								67,000	120,000	868,000	239,000
Interest and debt financing expenses								905,000	2,919,000	$ 4,857,000	5,317,000
Wells Fargo Financing Facility | Secured Overnight Financing Rate (SOFR) | Credit Facility | Secured Debt
Debt Instrument [Line Items]
Percentage of interest rate										2.20%		2.20%
Wells Fargo Financing Facility - Daily Undrawn Amounts During The Period | Credit Facility | Secured Debt
Debt Instrument [Line Items]
Unused commitment fee, percentage	0.25%
Wells Fargo Financing Facility - For Next Six Months And Thereafter | Credit Facility | Secured Debt
Debt Instrument [Line Items]
Unused commitment fee, percentage	0.50%
SMBC Financing Facility | Credit Facility | Secured Debt
Debt Instrument [Line Items]
Total Commitment		$ 150,000,000	$ 150,000,000	$ 300,000,000				150,000,000		$ 150,000,000		$ 150,000,000			$ 300,000,000
Amount available								36,240,000		36,240,000		$ 112,623,000
Unused commitment fee, percentage				0.50%
Subsequent increase			$ 250,000,000
Unused commitment fee percentage, less than fifty percent of total commitments			0.50%
Unused commitment fee percentage, more than fifty percent of total commitments			1.00%
Debt instrument, extension fee			$ 450,000
Annualized fee percentage			0.30%
Borrowing interest expense								1,541,000	4,899,000	2,098,000	9,315,000
Unused fees								103,000	36,000	169,000	80,000
Amortization of deferred financing costs								110,000	128,000	221,000	254,000
Interest and debt financing expenses								1,754,000	5,063,000	$ 2,488,000	9,649,000
SMBC Financing Facility | Secured Overnight Financing Rate (SOFR) | Credit Facility | Secured Debt
Debt Instrument [Line Items]
Percentage of interest rate			2.65%	2.15%						2.65%		2.65%
SMBC Financing Facility | Base Rate | Credit Facility | Secured Debt
Debt Instrument [Line Items]
Percentage of interest rate			1.65%	1.15%
Revolving Credit Facility | Credit Facility | Secured Debt
Debt Instrument [Line Items]
Total Commitment								250,000,000		$ 250,000,000		$ 185,000,000
Amount available								172,750,000		172,750,000		$ 58,500,000
Unused commitment fee, percentage					0.375%
Maximum borrowing capacity, including accordion feature					$ 300,000,000
Borrowing interest expense								1,090,000	0	1,714,000	0
Unused fees								186,000	17,000	332,000	17,000
Amortization of deferred financing costs								126,000	9,000	230,000	9,000
Interest and debt financing expenses								1,402,000	26,000	$ 2,276,000	26,000
Revolving Credit Facility | Credit Facility | Bridge Loan
Debt Instrument [Line Items]
Total Commitment					$ 25,000,000
Revolving Credit Facility | Secured Overnight Financing Rate (SOFR) | Credit Facility | Secured Debt
Debt Instrument [Line Items]
Percentage of interest rate										2.25%		2.25%
2022 Debt | Secured Debt
Debt Instrument [Line Items]
Total Commitment								342,000,000		$ 342,000,000		$ 342,000,000
Amount available								0		0		0
Debt securitization						$ 448,325,000
Borrowing interest expense								6,086,000	5,815,000	12,186,000	11,258,000
Unused fees								0	0	0	0
Amortization of deferred financing costs								150,000	150,000	300,000	298,000
Interest and debt financing expenses								6,236,000	5,965,000	12,486,000	11,556,000
AAA Class A-1 2022 Notes | Secured Debt
Debt Instrument [Line Items]
Debt securitization						$ 199,000,000
AAA Class A-1 2022 Notes | Secured Overnight Financing Rate (SOFR) | Secured Debt
Debt Instrument [Line Items]
Percentage of interest rate						1.80%
AAA Class A-1F 2022 Notes | Secured Debt
Debt Instrument [Line Items]
Percentage of interest rate						4.42%
Debt securitization						$ 34,250,000
AA Class B 2022 Notes | Secured Debt
Debt Instrument [Line Items]
Debt securitization						$ 47,250,000
AA Class B 2022 Notes | Secured Overnight Financing Rate (SOFR) | Secured Debt
Debt Instrument [Line Items]
Percentage of interest rate						2.30%
A Class C 2022 Notes | Secured Debt
Debt Instrument [Line Items]
Debt securitization						$ 31,500,000
A Class C 2022 Notes | Secured Overnight Financing Rate (SOFR) | Secured Debt
Debt Instrument [Line Items]
Percentage of interest rate						3.15%
BBB Class D 2022 Notes | Secured Debt
Debt Instrument [Line Items]
Debt securitization						$ 27,000,000
BBB Class D 2022 Notes | Secured Overnight Financing Rate (SOFR) | Secured Debt
Debt Instrument [Line Items]
Percentage of interest rate						4.15%
Subordinated 2022 Notes | Secured Debt
Debt Instrument [Line Items]
Debt securitization						$ 79,325,000
AAA Class A-L 2022 Loans to CLO-I | Secured Debt
Debt Instrument [Line Items]
Debt securitization						$ 30,000,000
AAA Class A-L 2022 Loans to CLO-I | Secured Overnight Financing Rate (SOFR) | Secured Debt
Debt Instrument [Line Items]
Percentage of interest rate						1.80%
2023 Debt | Secured Debt
Debt Instrument [Line Items]
Total Commitment								215,000,000		215,000,000		215,000,000
Amount available								0		0		$ 0
Debt securitization		298,060,000
Borrowing interest expense								4,231,000	0	8,472,000	0
Unused fees								0	0	0	0
Amortization of deferred financing costs								111,000	0	221,000	0
Interest and debt financing expenses								4,342,000	0	8,693,000	0
AAA Class X 2023 Notes | Secured Debt
Debt Instrument [Line Items]
Debt securitization		$ 2,000,000
AAA Class X 2023 Notes | Secured Overnight Financing Rate (SOFR) | Secured Debt
Debt Instrument [Line Items]
Percentage of interest rate		2.00%
AAA Class A-1 2023 Notes | Secured Debt
Debt Instrument [Line Items]
Debt securitization		$ 100,500,000
AAA Class A-1 2023 Notes | Secured Overnight Financing Rate (SOFR) | Secured Debt
Debt Instrument [Line Items]
Percentage of interest rate		2.35%
AA Class B 2023 Notes | Secured Debt
Debt Instrument [Line Items]
Debt securitization		$ 37,500,000
AA Class B 2023 Notes | Secured Overnight Financing Rate (SOFR) | Secured Debt
Debt Instrument [Line Items]
Percentage of interest rate		3.20%
Subordinated 2023 Notes | Secured Debt
Debt Instrument [Line Items]
Debt securitization		$ 83,060,000
AAA Class A-L-A 2023 to CLO-II | Secured Debt
Debt Instrument [Line Items]
Debt securitization		$ 25,000,000
AAA Class A-L-A 2023 to CLO-II | Secured Overnight Financing Rate (SOFR) | Secured Debt
Debt Instrument [Line Items]
Percentage of interest rate		2.35%
AAA Class A-L-B 2023 Loans to CLO-II | Secured Debt
Debt Instrument [Line Items]
Debt securitization		$ 50,000,000
AAA Class A-L-B 2023 Loans to CLO-II | Secured Overnight Financing Rate (SOFR) | Secured Debt
Debt Instrument [Line Items]
Percentage of interest rate		2.35%
2024 Debt | Secured Debt
Debt Instrument [Line Items]
Total Commitment								215,000,000		215,000,000
Amount available								0		0
Debt securitization	$ 296,970,000
Borrowing interest expense								3,983,000	0	4,743,000	0
Unused fees								0	0	0	0
Amortization of deferred financing costs								99,000	0	119,000	0
Interest and debt financing expenses								$ 4,082,000	$ 0	$ 4,862,000	$ 0
AAA Class X 2024 Notes | Secured Debt
Debt Instrument [Line Items]
Debt securitization	$ 2,000,000
AAA Class X 2024 Notes | Secured Overnight Financing Rate (SOFR) | Secured Debt
Debt Instrument [Line Items]
Percentage of interest rate	1.40%
AAA Class A 2024 Notes | Secured Debt
Debt Instrument [Line Items]
Debt securitization	$ 175,500,000
AAA Class A 2024 Notes | Secured Overnight Financing Rate (SOFR) | Secured Debt
Debt Instrument [Line Items]
Percentage of interest rate	2.00%
AA Class B 2024 Notes | Secured Debt
Debt Instrument [Line Items]
Debt securitization	$ 37,500,000
AA Class B 2024 Notes | Secured Overnight Financing Rate (SOFR) | Secured Debt
Debt Instrument [Line Items]
Percentage of interest rate	2.65%
Subordinated 2024 Notes | Secured Debt
Debt Instrument [Line Items]
Debt securitization	$ 81,970,000