Investments - Industry and Geographic Dispersion of Investment Portfolio as Percentage of Total Fair Value of Investments (Detail)	Dec. 31, 2019	Dec. 31, 2018
Investment Holdings [Line Items]
Percentage of total fair value of investment	100.00%	100.00%
Commercial and Professional Services
Investment Holdings [Line Items]
Percentage of total fair value of investment	39.20%	62.10%
Hobby Goods and Supplies
Investment Holdings [Line Items]
Percentage of total fair value of investment	21.70%	37.90%
Information Services and Advisory Solutions [Member]
Investment Holdings [Line Items]
Percentage of total fair value of investment	32.20%	0.00%
Manufacturing [Member]
Investment Holdings [Line Items]
Percentage of total fair value of investment	6.90%	0.00%
United States
Investment Holdings [Line Items]
Percentage of total fair value of investment	100.00%	100.00%