Investments - Summary of Unobservable Inputs Used in Fair Value Measurements of Level 3 Investments (Detail) - Level 3 $ in Thousands		Sep. 30, 2025 USD ($)		Dec. 31, 2024 USD ($)
Schedule of Investments [Line Items]
Assets Fair Value Disclosure		$ 3,125,278		$ 2,894,850
First Lien Secured Debt | Yield Analysis | Discount Rate
Schedule of Investments [Line Items]
Assets Fair Value Disclosure		$ 2,665,125		$ 2,409,833
First Lien Secured Debt | Yield Analysis | Minimum | Discount Rate
Schedule of Investments [Line Items]
Quantitative Information on Unobservable input		0.039		0.041
First Lien Secured Debt | Yield Analysis | Maximum | Discount Rate
Schedule of Investments [Line Items]
Quantitative Information on Unobservable input		0.425		0.314
First Lien Secured Debt | Yield Analysis | Weighted Average | Discount Rate
Schedule of Investments [Line Items]
Quantitative Information on Unobservable input	[1]	0.107		0.113
First Lien Secured Debt | Recent Transaction | Recent Transaction
Schedule of Investments [Line Items]
Assets Fair Value Disclosure		$ 81,862		$ 119,051
First Lien Secured Debt | Recovery Analysis | Recoverable Amount
Schedule of Investments [Line Items]
Assets Fair Value Disclosure		146,493		136,535
First Lien Secured Debt | Market Comparable Technique | Comparable Multiple
Schedule of Investments [Line Items]
Assets Fair Value Disclosure		$ 12,680		$ 10,765
First Lien Secured Debt | Market Comparable Technique | Minimum | Comparable Multiple
Schedule of Investments [Line Items]
Quantitative Information on Unobservable input		0.4		3.5
First Lien Secured Debt | Market Comparable Technique | Maximum | Comparable Multiple
Schedule of Investments [Line Items]
Quantitative Information on Unobservable input		4.8		3.5
First Lien Secured Debt | Market Comparable Technique | Weighted Average | Comparable Multiple
Schedule of Investments [Line Items]
Quantitative Information on Unobservable input		3.2	[1]	3.5	[2]
First Lien Secured Debt | Cost Approach | Cost Approach
Schedule of Investments [Line Items]
Assets Fair Value Disclosure		$ 49,499
First Lien Secured Debt | Transactional Value | Transactional Value
Schedule of Investments [Line Items]
Assets Fair Value Disclosure		4,494
First Lien Secured Debt | Broker Quote | Broker Quote
Schedule of Investments [Line Items]
Assets Fair Value Disclosure				$ 69
Second Lien Secured Debt | Yield Analysis | Discount Rate
Schedule of Investments [Line Items]
Assets Fair Value Disclosure		$ 72		$ 132
Second Lien Secured Debt | Yield Analysis | Minimum | Discount Rate
Schedule of Investments [Line Items]
Quantitative Information on Unobservable input		16.4		0.176
Second Lien Secured Debt | Yield Analysis | Maximum | Discount Rate
Schedule of Investments [Line Items]
Quantitative Information on Unobservable input		16.4		0.176
Second Lien Secured Debt | Yield Analysis | Weighted Average | Discount Rate
Schedule of Investments [Line Items]
Quantitative Information on Unobservable input		16.4	[1]	0.176	[2]
Second Lien Secured Debt | Recovery Analysis | Recoverable Amount
Schedule of Investments [Line Items]
Assets Fair Value Disclosure				$ 914
Second Lien Secured Debt | Recovery Analysis | Minimum | Recoverable Amount
Schedule of Investments [Line Items]
Quantitative Information on Unobservable input				3.5
Second Lien Secured Debt | Recovery Analysis | Maximum | Recoverable Amount
Schedule of Investments [Line Items]
Quantitative Information on Unobservable input				3.5
Second Lien Secured Debt | Recovery Analysis | Weighted Average | Recoverable Amount
Schedule of Investments [Line Items]
Quantitative Information on Unobservable input	[1]			3.5
Second Lien Secured Debt | Market Comparable Technique | Comparable Multiple
Schedule of Investments [Line Items]
Assets Fair Value Disclosure				$ 4,718
Second Lien Secured Debt | Market Comparable Technique | Minimum | Comparable Multiple
Schedule of Investments [Line Items]
Quantitative Information on Unobservable input				6.2
Second Lien Secured Debt | Market Comparable Technique | Maximum | Comparable Multiple
Schedule of Investments [Line Items]
Quantitative Information on Unobservable input				6.2
Second Lien Secured Debt | Market Comparable Technique | Weighted Average | Comparable Multiple
Schedule of Investments [Line Items]
Quantitative Information on Unobservable input	[2]			6.2
Unsecured Debt | Market Comparable Technique | Comparable Multiple
Schedule of Investments [Line Items]
Assets Fair Value Disclosure		$ 21		$ 117
Unsecured Debt | Market Comparable Technique | Minimum | Comparable Multiple
Schedule of Investments [Line Items]
Quantitative Information on Unobservable input		19.3		4.3
Unsecured Debt | Market Comparable Technique | Maximum | Comparable Multiple
Schedule of Investments [Line Items]
Quantitative Information on Unobservable input		19.3		4.3
Unsecured Debt | Market Comparable Technique | Weighted Average | Comparable Multiple
Schedule of Investments [Line Items]
Quantitative Information on Unobservable input	[1]	19.3		4.3
Structured Products And Other | Yield Analysis | Discount Rate
Schedule of Investments [Line Items]
Assets Fair Value Disclosure		$ 19,261		$ 26,101
Structured Products And Other | Yield Analysis | Minimum | Discount Rate
Schedule of Investments [Line Items]
Quantitative Information on Unobservable input		0.088		0.123
Structured Products And Other | Yield Analysis | Maximum | Discount Rate
Schedule of Investments [Line Items]
Quantitative Information on Unobservable input		0.13		0.113
Structured Products And Other | Yield Analysis | Weighted Average | Discount Rate
Schedule of Investments [Line Items]
Quantitative Information on Unobservable input		0.106	[1]	0.116	[2]
Preferred Equity | Yield Analysis | Discount Rate
Schedule of Investments [Line Items]
Assets Fair Value Disclosure		$ 454		$ 193
Preferred Equity | Yield Analysis | Minimum | Discount Rate
Schedule of Investments [Line Items]
Quantitative Information on Unobservable input		0.12		0.135
Preferred Equity | Yield Analysis | Maximum | Discount Rate
Schedule of Investments [Line Items]
Quantitative Information on Unobservable input		0.12		0.135
Preferred Equity | Yield Analysis | Weighted Average | Discount Rate
Schedule of Investments [Line Items]
Quantitative Information on Unobservable input		0.12	[1]	0.135	[2]
Preferred Equity | Recent Transaction | Recent Transaction
Schedule of Investments [Line Items]
Assets Fair Value Disclosure		$ 10,818		$ 519
Preferred Equity | Market Comparable Technique | Comparable Multiple
Schedule of Investments [Line Items]
Assets Fair Value Disclosure		$ 22,209		$ 24,119
Preferred Equity | Market Comparable Technique | Minimum | Comparable Multiple
Schedule of Investments [Line Items]
Quantitative Information on Unobservable input		0.4		2.3
Preferred Equity | Market Comparable Technique | Maximum | Comparable Multiple
Schedule of Investments [Line Items]
Quantitative Information on Unobservable input		16.8		17.8
Preferred Equity | Market Comparable Technique | Weighted Average | Comparable Multiple
Schedule of Investments [Line Items]
Quantitative Information on Unobservable input		9	[1]	10.8	[2]
Preferred Equity | Cost Approach | Cost Approach
Schedule of Investments [Line Items]
Assets Fair Value Disclosure		$ 100
Preferred Equity | Transactional Value | Transactional Value
Schedule of Investments [Line Items]
Assets Fair Value Disclosure		99
Common Equity/Interests | Yield Analysis | Discount Rate
Schedule of Investments [Line Items]
Assets Fair Value Disclosure		$ 79,159		$ 124,215
Common Equity/Interests | Yield Analysis | Minimum | Discount Rate
Schedule of Investments [Line Items]
Quantitative Information on Unobservable input		0.12		0.096
Common Equity/Interests | Yield Analysis | Maximum | Discount Rate
Schedule of Investments [Line Items]
Quantitative Information on Unobservable input		0.13		0.135
Common Equity/Interests | Yield Analysis | Weighted Average | Discount Rate
Schedule of Investments [Line Items]
Quantitative Information on Unobservable input		0	[1]	0.096	[2]
Common Equity/Interests | Recent Transaction | Recent Transaction
Schedule of Investments [Line Items]
Assets Fair Value Disclosure		$ 49		$ 218
Common Equity/Interests | Market Comparable Technique | Comparable Multiple
Schedule of Investments [Line Items]
Assets Fair Value Disclosure		$ 13,298		$ 17,838
Common Equity/Interests | Market Comparable Technique | Minimum | Comparable Multiple
Schedule of Investments [Line Items]
Quantitative Information on Unobservable input		0.4		0.7
Common Equity/Interests | Market Comparable Technique | Maximum | Comparable Multiple
Schedule of Investments [Line Items]
Quantitative Information on Unobservable input		19.3		22
Common Equity/Interests | Market Comparable Technique | Weighted Average | Comparable Multiple
Schedule of Investments [Line Items]
Quantitative Information on Unobservable input	[1]	5.5		11.3
Common Equity/Interests | Transactional Value | Transactional Value
Schedule of Investments [Line Items]
Assets Fair Value Disclosure		$ 715
Common Equity/Interests | Estimated Proceeds | Estimated Proceeds
Schedule of Investments [Line Items]
Assets Fair Value Disclosure		18,515		$ 18,933
Common Equity/Interests | Option Pricing Model | Expected Volatility
Schedule of Investments [Line Items]
Assets Fair Value Disclosure		$ 133		$ 444
Common Equity/Interests | Option Pricing Model | Minimum | Expected Volatility
Schedule of Investments [Line Items]
Quantitative Information on Unobservable input		0.95		0.25
Common Equity/Interests | Option Pricing Model | Maximum | Expected Volatility
Schedule of Investments [Line Items]
Quantitative Information on Unobservable input		0.95		0.85
Common Equity/Interests | Option Pricing Model | Weighted Average | Expected Volatility
Schedule of Investments [Line Items]
Quantitative Information on Unobservable input		0.487	[1]	0.343	[2]
Warrants - Warrants | Market Comparable Technique | Comparable Multiple
Schedule of Investments [Line Items]
Assets Fair Value Disclosure		$ 9
Warrants - Warrants | Market Comparable Technique | Minimum | Comparable Multiple
Schedule of Investments [Line Items]
Quantitative Information on Unobservable input		19.3		4.3
Warrants - Warrants | Market Comparable Technique | Maximum | Comparable Multiple
Schedule of Investments [Line Items]
Quantitative Information on Unobservable input		0.193		4.3
Warrants - Warrants | Market Comparable Technique | Weighted Average | Comparable Multiple
Schedule of Investments [Line Items]
Quantitative Information on Unobservable input		19.3	[1]	4.3	[2]
Warrants - Warrants | Transactional Value | Transactional Value
Schedule of Investments [Line Items]
Assets Fair Value Disclosure		$ 14
Warrants - Warrants | Option Pricing Model | Expected Volatility
Schedule of Investments [Line Items]
Assets Fair Value Disclosure		$ 198		$ 136
Warrants - Warrants | Option Pricing Model | Minimum | Expected Volatility
Schedule of Investments [Line Items]
Quantitative Information on Unobservable input		0.50		0.50
Warrants - Warrants | Option Pricing Model | Maximum | Expected Volatility
Schedule of Investments [Line Items]
Quantitative Information on Unobservable input		0.50		0.50
Warrants - Warrants | Option Pricing Model | Weighted Average | Expected Volatility
Schedule of Investments [Line Items]
Quantitative Information on Unobservable input		0.50	[1]	0.50	[2]

[1] The weighted average information is generally derived by assigning each disclosed unobservable input a proportionate weight based on the fair value of the related investment. For the commodity price unobservable input, the weighted average price is an undiscounted price based upon the estimated production level from the underlying reserves.

[2] The weighted average information is generally derived by assigning each disclosed unobservable input a proportionate weight based on the fair value of the related investment. For the commodity price unobservable input, the weighted average price is an undiscounted price based upon the estimated production level from the underlying reserves.