INVESTMENTS - Portfolio by Industry Grouping (Details) - USD ($) $ in Thousands	Dec. 31, 2025	Dec. 31, 2024
Investments, fair value	$ 578,649	$ 642,213
Percent of net assets	222.70%	224.40%
Investments Excluding STRS JV's
Investments, fair value	$ 472,631	$ 535,056
Percent of net assets	100.00%	100.00%
Investments Excluding STRS JV's \| Advertising
Investments, fair value	$ 1,518	$ 17,451
Percent of net assets	0.30%	3.30%
Investments Excluding STRS JV's \| Air Freight & Logistics
Investments, fair value	$ 31,528	$ 28,518
Percent of net assets	6.70%	5.30%
Investments Excluding STRS JV's \| Application Software
Investments, fair value	$ 22,741	$ 26,924
Percent of net assets	4.80%	5.00%
Investments Excluding STRS JV's \| Broadcasting
Investments, fair value		$ 7,833
Percent of net assets		1.50%
Investments Excluding STRS JV's \| Broadline Retail
Investments, fair value	$ 735	$ 5,336
Percent of net assets	0.20%	1.00%
Investments Excluding STRS JV's \| Building Products
Investments, fair value	$ 13,748	$ 13,206
Percent of net assets	2.90%	2.50%
Investments Excluding STRS JV's \| Commodity Chemicals
Investments, fair value		$ 16,026
Percent of net assets		3.00%
Investments Excluding STRS JV's \| Construction & Engineering
Investments, fair value	$ 9,906	$ 3,927
Percent of net assets	2.10%	0.70%
Investments Excluding STRS JV's \| Construction Materials
Investments, fair value	$ 5,159	$ 5,640
Percent of net assets	1.10%	1.10%
Investments Excluding STRS JV's \| Data Processing & Outsourced Services
Investments, fair value	$ 26,789	$ 28,572
Percent of net assets	5.70%	5.30%
Investments Excluding STRS JV's \| Distributors
Investments, fair value	$ 10,404	$ 10,690
Percent of net assets	2.20%	2.00%
Investments Excluding STRS JV's \| Diversified Chemicals
Investments, fair value	$ 8,188	$ 4,999
Percent of net assets	1.70%	0.90%
Investments Excluding STRS JV's \| Diversified Support Services
Investments, fair value	$ 9,337	$ 9,563
Percent of net assets	2.00%	1.80%
Investments Excluding STRS JV's \| Education Services
Investments, fair value	$ 20,007	$ 21,314
Percent of net assets	4.20%	4.00%
Investments Excluding STRS JV's \| Electric Utilities
Investments, fair value		$ 16,032
Percent of net assets		3.00%
Investments Excluding STRS JV's \| Environmental & Facilities Services
Investments, fair value	$ 3,255	$ 1,400
Percent of net assets	0.70%	0.30%
Investments Excluding STRS JV's \| Food Distributors
Investments, fair value	$ 264	$ 350
Percent of net assets	0.10%	0.10%
Investments Excluding STRS JV's \| Health Care Facilities
Investments, fair value	$ 4,623	$ 8,660
Percent of net assets	1.00%	1.60%
Investments Excluding STRS JV's \| Health Care Services
Investments, fair value	$ 8,389	$ 19,589
Percent of net assets	1.80%	3.70%
Investments Excluding STRS JV's \| Health Care Supplies
Investments, fair value	$ 20,026	$ 19,535
Percent of net assets	4.20%	3.70%
Investments Excluding STRS JV's \| Heavy Electrical Equipment
Investments, fair value		$ 10,138
Percent of net assets		1.90%
Investments Excluding STRS JV's \| Home Furnishings
Investments, fair value	$ 16,103	$ 25,376
Percent of net assets	3.40%	4.70%
Investments Excluding STRS JV's \| Household Appliances
Investments, fair value	$ 2,202	$ 22,162
Percent of net assets	0.50%	4.10%
Investments Excluding STRS JV's \| Household Products
Investments, fair value	$ 9,658	$ 11,656
Percent of net assets	2.00%	2.20%
Investments Excluding STRS JV's \| Human Resource & Employment Services
Investments, fair value	$ 2,909
Percent of net assets	0.60%
Investments Excluding STRS JV's \| Industrial Machinery & Supplies & Components
Investments, fair value	$ 12,895	$ 13,237
Percent of net assets	2.70%	2.50%
Investments Excluding STRS JV's \| Integrated Telecommunication Services
Investments, fair value	$ 26,732	$ 13,135
Percent of net assets	5.70%	2.50%
Investments Excluding STRS JV's \| Interactive Media & Services
Investments, fair value	$ 15,940	$ 15,970
Percent of net assets	3.40%	3.00%
Investments Excluding STRS JV's \| IT Consulting & Other Services
Investments, fair value	$ 1,287	$ 3,504
Percent of net assets	0.30%	0.60%
Investments Excluding STRS JV's \| Leisure Facilities
Investments, fair value	$ 15,233	$ 19,580
Percent of net assets	3.20%	3.70%
Investments Excluding STRS JV's \| Leisure Products
Investments, fair value	$ 23,767	$ 23,298
Percent of net assets	5.00%	4.40%
Investments Excluding STRS JV's \| Life Sciences Tools & Services
Investments, fair value		$ 5,000
Percent of net assets		0.90%
Investments Excluding STRS JV's \| Oil & Gas Storage & Transportation
Investments, fair value	$ 10,158
Percent of net assets	2.10%
Investments Excluding STRS JV's \| Packaged Foods & Meats
Investments, fair value	$ 4,033	$ 4,087
Percent of net assets	0.90%	0.70%
Investments Excluding STRS JV's \| Paper Products
Investments, fair value	$ 9,276	$ 9,453
Percent of net assets	2.00%	1.80%
Investments Excluding STRS JV's \| Pharmaceuticals
Investments, fair value	$ 12,027
Percent of net assets	2.50%
Investments Excluding STRS JV's \| Real Estate Services
Investments, fair value	$ 20,426	$ 20,872
Percent of net assets	4.30%	3.90%
Investments Excluding STRS JV's \| Research & Consulting Services
Investments, fair value	$ 5,143	$ 5,295
Percent of net assets	1.10%	0.90%
Investments Excluding STRS JV's \| Security & Alarm Services
Investments, fair value		$ 7,070
Percent of net assets		1.30%
Investments Excluding STRS JV's \| Specialized Consumer Services
Investments, fair value	$ 19,461	$ 7,122
Percent of net assets	4.10%	1.30%
Investments Excluding STRS JV's \| Specialized Finance
Investments, fair value	$ 10,661
Percent of net assets	2.30%
Investments Excluding STRS JV's \| Systems Software
Investments, fair value	$ 28,504	$ 26,398
Percent of net assets	6.00%	4.90%
Investments Excluding STRS JV's \| Technology Hardware, Storage & Peripherals
Investments, fair value	$ 19,484	$ 18,072
Percent of net assets	4.10%	3.40%
Investments Excluding STRS JV's \| Transaction & Payment Processing Services
Investments, fair value	$ 10,115	$ 8,066
Percent of net assets	2.10%	1.50%