Fair Value of Financial Instruments - Investments Categorization in Fair Value Hierarchy (Detail) - USD ($) $ in Thousands	Mar. 31, 2022		Dec. 31, 2021
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Total investments	$ 468,654	[1],[2]	$ 455,997	[3],[4]
Level 1
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Total investments	0		0
Level 2
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Total investments	0		0
Level 3
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Total investments	468,654		455,997
Total Senior Secured Notes
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Senior secured debt	152,542		152,542
Total investments	152,542	[1],[2]	152,542	[3],[4]
Total Senior Secured Notes | Level 1
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Senior secured debt	0		0
Total Senior Secured Notes | Level 2
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Senior secured debt	0		0
Total Senior Secured Notes | Level 3
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Senior secured debt	152,542		152,542
Equity
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Equity	316,112		303,455
Total investments	316,112	[1],[2]	303,455	[3],[4]
Equity | Level 1
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Equity	0		0
Equity | Level 2
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Equity	0		0
Equity | Level 3
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Equity	$ 316,112		$ 303,455

[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.