Investments - Industry and Geographic Dispersion of Investment Portfolio as Percentage of Total Fair Value of Investments (Detail)	Mar. 31, 2022	Dec. 31, 2021
Investment Holdings [Line Items]
Percentage of total fair value of investment	100.00%	100.00%
Real Estate Services
Investment Holdings [Line Items]
Percentage of total fair value of investment	16.80%	17.20%
Commercial and Professional Services
Investment Holdings [Line Items]
Percentage of total fair value of investment	16.30%	15.80%
Visual Safety Solutions
Investment Holdings [Line Items]
Percentage of total fair value of investment	14.80%	15.20%
Information Services and Advisory Solutions
Investment Holdings [Line Items]
Percentage of total fair value of investment	11.40%	12.10%
Healthcare Supplies
Investment Holdings [Line Items]
Percentage of total fair value of investment	11.40%	10.60%
Sanitation Products
Investment Holdings [Line Items]
Percentage of total fair value of investment	10.90%	11.10%
Hobby Goods and Supplies
Investment Holdings [Line Items]
Percentage of total fair value of investment	8.20%	8.70%
Engineered Products
Investment Holdings [Line Items]
Percentage of total fair value of investment	2.90%	2.80%
Business Services
Investment Holdings [Line Items]
Percentage of total fair value of investment	7.30%	6.50%