Fair Value of Financial Instruments - Investments Categorization in Fair Value Hierarchy (Detail) - USD ($) $ in Thousands	Sep. 30, 2022	Dec. 31, 2021
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Investments at fair value	$ 633,001	$ 455,997	[1],[2]
Total Senior Secured Notes
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Senior secured debt	176,942	152,542
Equity
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Equity	395,984	303,455
U.S. Treasury Bills
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Investments at fair value	60,075	0
Level 1
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Investments at fair value	60,075	0
Level 1 | Total Senior Secured Notes
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Senior secured debt	0	0
Level 1 | Equity
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Equity	0	0
Level 1 | U.S. Treasury Bills
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Investments at fair value	60,075	0
Level 2
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Investments at fair value	0	0
Level 2 | Total Senior Secured Notes
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Senior secured debt	0	0
Level 2 | Equity
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Equity	0	0
Level 2 | U.S. Treasury Bills
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Investments at fair value	0	0
Level 3
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Investments at fair value	572,926	455,997
Level 3 | Total Senior Secured Notes
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Senior secured debt	176,942	152,542
Level 3 | Equity
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Equity	395,984	303,455
Level 3 | U.S. Treasury Bills
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Investments at fair value	$ 0	$ 0

[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.