CONSOLIDATED SCHEDULE OF INVESTMENTS (Parenthetical 2) - USD ($) $ in Thousands	3 Months Ended		12 Months Ended
	Mar. 31, 2024		Dec. 31, 2023
Schedule of Investments [Line Items]
Amortized cost	$ 1,829,575		$ 1,904,895
Investments, at fair value	1,784,893	[1]	1,841,881	[2]
Australia
Schedule of Investments [Line Items]
Amortized cost	5,029		5,023
Investments, at fair value	5,150		5,139
Canada
Schedule of Investments [Line Items]
Amortized cost	50,822		50,490
Investments, at fair value	52,008		51,711
Luxembourg
Schedule of Investments [Line Items]
Amortized cost	42,119		41,755
Investments, at fair value	40,165		40,095
Sweden
Schedule of Investments [Line Items]
Amortized cost	1,168		1,168
Investments, at fair value	266		395
United Kingdom
Schedule of Investments [Line Items]
Amortized cost	79,469		75,844
Investments, at fair value	76,711		73,713
United States
Schedule of Investments [Line Items]
Amortized cost	1,650,968		1,730,615
Investments, at fair value	$ 1,610,593		$ 1,670,828
Investments at fair value | Industry concentration
Schedule of Investments [Line Items]
Concentration risk percentage	100.00%		100.00%
Investments at fair value | Geographic concentration
Schedule of Investments [Line Items]
Concentration risk percentage	100.00%		100.00%
Investments at fair value | Geographic concentration | Australia
Schedule of Investments [Line Items]
Concentration risk percentage	0.30%		0.30%
Investments at fair value | Geographic concentration | Canada
Schedule of Investments [Line Items]
Concentration risk percentage	2.90%		2.80%
Investments at fair value | Geographic concentration | Luxembourg
Schedule of Investments [Line Items]
Concentration risk percentage	2.30%		2.20%
Investments at fair value | Geographic concentration | Sweden
Schedule of Investments [Line Items]
Concentration risk percentage	0.00%		0.00%
Investments at fair value | Geographic concentration | United Kingdom
Schedule of Investments [Line Items]
Concentration risk percentage	4.30%		4.00%
Investments at fair value | Geographic concentration | United States
Schedule of Investments [Line Items]
Concentration risk percentage	90.20%		90.70%
Aerospace & Defense
Schedule of Investments [Line Items]
Amortized cost	$ 108,530		$ 110,041
Investments, at fair value	$ 101,054		$ 102,939
Aerospace & Defense | Investments at fair value | Industry concentration
Schedule of Investments [Line Items]
Concentration risk percentage	5.70%		5.60%
Automotive
Schedule of Investments [Line Items]
Amortized cost	$ 76,210		$ 75,867
Investments, at fair value	$ 74,691		$ 74,333
Automotive | Investments at fair value | Industry concentration
Schedule of Investments [Line Items]
Concentration risk percentage	4.20%		4.00%
Beverage & Food
Schedule of Investments [Line Items]
Amortized cost	$ 49,671		$ 63,382
Investments, at fair value	$ 46,906		$ 60,198
Beverage & Food | Investments at fair value | Industry concentration
Schedule of Investments [Line Items]
Concentration risk percentage	2.60%		3.30%
Business Services
Schedule of Investments [Line Items]
Amortized cost	$ 98,297		$ 108,056
Investments, at fair value	$ 99,739		$ 108,862
Business Services | Investments at fair value | Industry concentration
Schedule of Investments [Line Items]
Concentration risk percentage	5.60%		5.90%
Capital Equipment
Schedule of Investments [Line Items]
Amortized cost	$ 42,622		$ 42,256
Investments, at fair value	$ 46,831		$ 45,687
Capital Equipment | Investments at fair value | Industry concentration
Schedule of Investments [Line Items]
Concentration risk percentage	2.60%		2.50%
Chemicals, Plastics & Rubber
Schedule of Investments [Line Items]
Amortized cost	$ 69,265		$ 69,178
Investments, at fair value	$ 67,970		$ 67,344
Chemicals, Plastics & Rubber | Investments at fair value | Industry concentration
Schedule of Investments [Line Items]
Concentration risk percentage	3.80%		3.70%
Construction & Building
Schedule of Investments [Line Items]
Amortized cost	$ 29,966		$ 25,825
Investments, at fair value	$ 30,375		$ 26,014
Construction & Building | Investments at fair value | Industry concentration
Schedule of Investments [Line Items]
Concentration risk percentage	1.70%		1.40%
Consumer Goods: Durable
Schedule of Investments [Line Items]
Amortized cost	$ 4,754		$ 5,373
Investments, at fair value	$ 4,621		$ 5,552
Consumer Goods: Durable | Investments at fair value | Industry concentration
Schedule of Investments [Line Items]
Concentration risk percentage	0.30%		0.30%
Consumer Goods: Non-Durable
Schedule of Investments [Line Items]
Amortized cost	$ 7,057		$ 7,062
Investments, at fair value	$ 7,308		$ 7,244
Consumer Goods: Non-Durable | Investments at fair value | Industry concentration
Schedule of Investments [Line Items]
Concentration risk percentage	0.40%		0.40%
Consumer Services
Schedule of Investments [Line Items]
Amortized cost	$ 93,716		$ 82,904
Investments, at fair value	$ 91,725		$ 80,668
Consumer Services | Investments at fair value | Industry concentration
Schedule of Investments [Line Items]
Concentration risk percentage	5.10%		4.40%
Containers, Packaging & Glass
Schedule of Investments [Line Items]
Amortized cost	$ 46,951		$ 46,473
Investments, at fair value	$ 40,982		$ 40,285
Containers, Packaging & Glass | Investments at fair value | Industry concentration
Schedule of Investments [Line Items]
Concentration risk percentage	2.30%		2.20%
Diversified Financial Services
Schedule of Investments [Line Items]
Amortized cost	$ 94,771		$ 90,796
Investments, at fair value	$ 94,943		$ 91,535
Diversified Financial Services | Investments at fair value | Industry concentration
Schedule of Investments [Line Items]
Concentration risk percentage	5.30%		5.00%
Energy: Oil & Gas
Schedule of Investments [Line Items]
Amortized cost	$ 12,332		$ 11,972
Investments, at fair value	$ 12,928		$ 12,341
Energy: Oil & Gas | Investments at fair value | Industry concentration
Schedule of Investments [Line Items]
Concentration risk percentage	0.70%		0.70%
Environmental Industries
Schedule of Investments [Line Items]
Amortized cost	$ 42,826		$ 39,572
Investments, at fair value	$ 42,950		$ 39,682
Environmental Industries | Investments at fair value | Industry concentration
Schedule of Investments [Line Items]
Concentration risk percentage	2.40%		2.20%
Healthcare & Pharmaceuticals
Schedule of Investments [Line Items]
Amortized cost	$ 215,340		$ 239,647
Investments, at fair value	$ 212,015		$ 213,649
Healthcare & Pharmaceuticals | Investments at fair value | Industry concentration
Schedule of Investments [Line Items]
Concentration risk percentage	12.00%		11.60%
High Tech Industries
Schedule of Investments [Line Items]
Amortized cost	$ 134,495		$ 136,374
Investments, at fair value	$ 135,440		$ 137,378
High Tech Industries | Investments at fair value | Industry concentration
Schedule of Investments [Line Items]
Concentration risk percentage	7.60%		7.50%
Investment Funds
Schedule of Investments [Line Items]
Amortized cost	$ 271,097		$ 271,097
Investments, at fair value	$ 248,598		$ 249,379
Investment Funds | Investments at fair value | Industry concentration
Schedule of Investments [Line Items]
Concentration risk percentage	13.90%		13.40%
Leisure Products & Services
Schedule of Investments [Line Items]
Amortized cost	$ 83,673		$ 130,116
Investments, at fair value	$ 79,385		$ 131,916
Leisure Products & Services | Investments at fair value | Industry concentration
Schedule of Investments [Line Items]
Concentration risk percentage	4.50%		7.20%
Media: Advertising, Printing & Publishing
Schedule of Investments [Line Items]
Amortized cost	$ 43,177		$ 44,362
Investments, at fair value	$ 43,650		$ 44,530
Media: Advertising, Printing & Publishing | Investments at fair value | Industry concentration
Schedule of Investments [Line Items]
Concentration risk percentage	2.40%		2.40%
Retail
Schedule of Investments [Line Items]
Amortized cost	$ 24,463		$ 29,558
Investments, at fair value	$ 24,885		$ 29,993
Retail | Investments at fair value | Industry concentration
Schedule of Investments [Line Items]
Concentration risk percentage	1.40%		1.60%
Software
Schedule of Investments [Line Items]
Amortized cost	$ 170,460		$ 166,536
Investments, at fair value	$ 172,102		$ 168,106
Software | Investments at fair value | Industry concentration
Schedule of Investments [Line Items]
Concentration risk percentage	9.60%		9.10%
Sovereign & Public Finance
Schedule of Investments [Line Items]
Amortized cost	$ 78		$ 78
Investments, at fair value	$ 80		$ 79
Sovereign & Public Finance | Investments at fair value | Industry concentration
Schedule of Investments [Line Items]
Concentration risk percentage	0.00%		0.00%
Telecommunications
Schedule of Investments [Line Items]
Amortized cost	$ 79,915		$ 78,772
Investments, at fair value	$ 75,697		$ 74,499
Telecommunications | Investments at fair value | Industry concentration
Schedule of Investments [Line Items]
Concentration risk percentage	4.20%		4.00%
Transportation: Cargo
Schedule of Investments [Line Items]
Amortized cost	$ 9,770		$ 9,430
Investments, at fair value	$ 9,284		$ 9,128
Transportation: Cargo | Investments at fair value | Industry concentration
Schedule of Investments [Line Items]
Concentration risk percentage	0.50%		0.50%
Utilities: Electric
Schedule of Investments [Line Items]
Amortized cost	$ 920		$ 920
Investments, at fair value	$ 910		$ 902
Utilities: Electric | Investments at fair value | Industry concentration
Schedule of Investments [Line Items]
Concentration risk percentage	0.10%		0.00%
Wholesale
Schedule of Investments [Line Items]
Amortized cost	$ 19,219		$ 19,248
Investments, at fair value	$ 19,824		$ 19,638
Wholesale | Investments at fair value | Industry concentration
Schedule of Investments [Line Items]
Concentration risk percentage	1.10%		1.10%

[1] The Company has determined the indicated investments are non-qualifying assets under Section 55(a) of the Investment Company Act. Under the Investment Company Act, the Company may not acquire any non-qualifying assets unless, at the time such acquisition is made, qualifying assets represent at least 70% of the Company’s total assets.

[2] Fair value is determined in good faith by or under the direction of the Investment Adviser, as the valuation designee pursuant to Rule 2a-5 under the Investment Company Act (see Note 2, Significant Accounting Policies, and Note 3, Fair Value Measurements, to these unaudited consolidated financial statements), pursuant to the Company’s valuation policy. The fair value of all first lien and second lien debt investments, equity investments and the investment fund was determined using significant unobservable inputs.