Investments - Summary of Investment Portfolio (Detail) - USD ($) $ in Thousands	Mar. 31, 2022		Dec. 31, 2021
Cost
Total investments	$ 388,642	[1],[2]	$ 387,754	[3],[4]
Fair Value
Total investments	$ 468,654	[1],[2]	$ 455,997	[3],[4]
Fair Value Percentage of Investment Portfolio	100.00%		100.00%
Fair Value Percentage of Net Assets	86.60%		91.20%
Total Senior Secured Notes
Cost
Senior secured debt	$ 152,542		$ 152,542
Fair Value
Senior secured debt	$ 152,542		$ 152,542
Fair Value Percentage of Investment Portfolio	32.50%		33.50%
Fair Value Percentage of Net Assets	28.20%		30.50%
First lien
Cost
Senior secured debt	$ 101,600		$ 116,600
Fair Value
Senior secured debt	$ 101,600		$ 116,600
Fair Value Percentage of Investment Portfolio	21.70%		25.60%
Fair Value Percentage of Net Assets	18.80%		23.30%
Second lien
Cost
Senior secured debt	$ 50,942		$ 35,942
Fair Value
Senior secured debt	$ 50,942		$ 35,942
Fair Value Percentage of Investment Portfolio	10.80%		7.90%
Fair Value Percentage of Net Assets	9.40%		7.20%
Equity
Cost
Equity	$ 236,100		$ 235,212
Fair Value
Equity	$ 316,112		$ 303,455
Fair Value Percentage of Investment Portfolio	67.50%		66.50%
Fair Value Percentage of Net Assets	58.40%		60.70%

[1] Percentages represent fair value as a percentage of net assets for each investment category.

[2] Security may be an obligation of one or more entities affiliated with the named company.

[3] Percentages represent fair value as a percentage of net assets for each investment category.

[4] Security may be an obligation of one or more entities affiliated with the named company.