Fair Value of Financial Instruments - Unobservable Inputs Used in Fair Value Measurement of Investments (Detail) $ in Thousands	Mar. 31, 2022 USD ($)		Dec. 31, 2021 USD ($)
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Total investments	$ 468,654	[1],[2]	$ 455,997	[3],[4]
Level 3
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Total investments	468,654		455,997
Discounted Cash Flow | Level 3
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Senior secured debt	152,542		130,042
Equity	$ 316,112		256,695
Transaction Precedent | Level 3
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Senior secured debt			22,500
Equity			$ 46,760
Minimum | Discounted Cash Flow | Discount Rate | Level 3
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Measurement input, Debt securities	0.090		0.085
Measurement input, Equity Securities	0.090		0.085
Minimum | Market Comparables | EBITDA Multiple | Level 3
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Measurement input, Debt securities	5.0		4.1
Measurement input, Equity Securities	5.0		4.1
Minimum | Transaction Method | EBITDA Multiple | Level 3
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Measurement input, Debt securities	6.5		6.0
Measurement input, Equity Securities	6.5		6.0
Maximum | Discounted Cash Flow | Discount Rate | Level 3
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Measurement input, Debt securities	0.135		0.130
Measurement input, Equity Securities	0.135		0.130
Maximum | Market Comparables | EBITDA Multiple | Level 3
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Measurement input, Debt securities	14.3		15.2
Measurement input, Equity Securities	14.3		15.2
Maximum | Transaction Method | EBITDA Multiple | Level 3
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Measurement input, Debt securities	13.0		12.5
Measurement input, Equity Securities	13.0		12.5
Weighted Average | Discounted Cash Flow | Discount Rate | Level 3
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Measurement input, Debt securities	0.113		0.114
Measurement input, Equity Securities	0.113		0.114
Weighted Average | Market Comparables | EBITDA Multiple | Level 3
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Measurement input, Debt securities	10.0		8.9
Measurement input, Equity Securities	10.0		8.9
Weighted Average | Transaction Method | EBITDA Multiple | Level 3
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Measurement input, Debt securities	10.5		9.6
Measurement input, Equity Securities	10.5		9.6

[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.