Investments - Summary of Unobservable Inputs Used in Fair Value Measurements of Level 3 Investments (Detail) - Level 3 $ in Thousands		Dec. 31, 2023 USD ($)	Dec. 31, 2022 USD ($)
Schedule of Investments [Line Items]
Assets Fair Value Disclosure		$ 2,332,982	$ 2,396,036
First Lien Secured Debt | Discounted Cash Flow | Discount Rate
Schedule of Investments [Line Items]
Assets Fair Value Disclosure			$ 150,000
First Lien Secured Debt | Discounted Cash Flow | Minimum | Discount Rate
Schedule of Investments [Line Items]
Quantitative Information on Unobservable input			0.114
First Lien Secured Debt | Discounted Cash Flow | Maximum | Discount Rate
Schedule of Investments [Line Items]
Quantitative Information on Unobservable input			0.120
First Lien Secured Debt | Discounted Cash Flow | Weighted Average | Discount Rate
Schedule of Investments [Line Items]
Quantitative Information on Unobservable input	[1]		0.120
First Lien Secured Debt | Recent Transaction | Recent Transaction
Schedule of Investments [Line Items]
Assets Fair Value Disclosure		59,746	$ 69,333
First Lien Secured Debt | Recovery Analysis | Recoverable Amount
Schedule of Investments [Line Items]
Assets Fair Value Disclosure			2,539
First Lien Secured Debt | Recovery Analysis | Recoverable Amount
Schedule of Investments [Line Items]
Assets Fair Value Disclosure		111,468
First Lien Secured Debt | Yield Analysis | Discount Rate
Schedule of Investments [Line Items]
Assets Fair Value Disclosure		$ 1,903,817	$ 1,908,437
First Lien Secured Debt | Yield Analysis | Minimum | Discount Rate
Schedule of Investments [Line Items]
Quantitative Information on Unobservable input		0.066	0.071
First Lien Secured Debt | Yield Analysis | Maximum | Discount Rate
Schedule of Investments [Line Items]
Quantitative Information on Unobservable input		0.251	0.528
First Lien Secured Debt | Yield Analysis | Weighted Average | Discount Rate
Schedule of Investments [Line Items]
Quantitative Information on Unobservable input	[1]	0.122	0.120
Second Lien Secured Debt | Recovery Analysis | Recoverable Amount
Schedule of Investments [Line Items]
Assets Fair Value Disclosure		$ 238	$ 1,402
Second Lien Secured Debt | Yield Analysis | Discount Rate
Schedule of Investments [Line Items]
Assets Fair Value Disclosure		$ 29,442	$ 62,849
Second Lien Secured Debt | Yield Analysis | Minimum | Discount Rate
Schedule of Investments [Line Items]
Quantitative Information on Unobservable input		0.137	0.133
Second Lien Secured Debt | Yield Analysis | Maximum | Discount Rate
Schedule of Investments [Line Items]
Quantitative Information on Unobservable input		0.258	0.231
Second Lien Secured Debt | Yield Analysis | Weighted Average | Discount Rate
Schedule of Investments [Line Items]
Quantitative Information on Unobservable input	[1]	0.173	0.155
Second Lien Secured Debt | Sale Proceeds | Sale Proceeds
Schedule of Investments [Line Items]
Assets Fair Value Disclosure			$ 239
Second Lien Secured Debt | Market Comparable Technique | Comparable Multiple
Schedule of Investments [Line Items]
Assets Fair Value Disclosure		$ 2,207	$ 6,429
Second Lien Secured Debt | Market Comparable Technique | Minimum | Comparable Multiple
Schedule of Investments [Line Items]
Quantitative Information on Unobservable input		8.5	11.0
Second Lien Secured Debt | Market Comparable Technique | Maximum | Comparable Multiple
Schedule of Investments [Line Items]
Quantitative Information on Unobservable input		8.5	11.0
Second Lien Secured Debt | Market Comparable Technique | Weighted Average | Comparable Multiple
Schedule of Investments [Line Items]
Quantitative Information on Unobservable input	[1]	8.5	11.0
Structured Products And Other | Yield Analysis | Discount Rate
Schedule of Investments [Line Items]
Assets Fair Value Disclosure		$ 41,333	$ 9,413
Structured Products And Other | Yield Analysis | Minimum | Discount Rate
Schedule of Investments [Line Items]
Quantitative Information on Unobservable input		0.13	0.123
Structured Products And Other | Yield Analysis | Maximum | Discount Rate
Schedule of Investments [Line Items]
Quantitative Information on Unobservable input		0.156	0.123
Structured Products And Other | Yield Analysis | Weighted Average | Discount Rate
Schedule of Investments [Line Items]
Quantitative Information on Unobservable input	[1]	0.149	0.123
Preferred Equity | Residual Value | Residual Value
Schedule of Investments [Line Items]
Assets Fair Value Disclosure		$ 78	$ 78
Preferred Equity | Recent Transaction | Recent Transaction
Schedule of Investments [Line Items]
Assets Fair Value Disclosure		268	250
Preferred Equity | Recovery Analysis | Recoverable Amount
Schedule of Investments [Line Items]
Assets Fair Value Disclosure			11
Preferred Equity | Yield Analysis | Discount Rate
Schedule of Investments [Line Items]
Assets Fair Value Disclosure		$ 109	$ 74
Preferred Equity | Yield Analysis | Minimum | Discount Rate
Schedule of Investments [Line Items]
Quantitative Information on Unobservable input		0.135	0.125
Preferred Equity | Yield Analysis | Maximum | Discount Rate
Schedule of Investments [Line Items]
Quantitative Information on Unobservable input		0.135	0.125
Preferred Equity | Yield Analysis | Weighted Average | Discount Rate
Schedule of Investments [Line Items]
Quantitative Information on Unobservable input	[1]	0.135	0.125
Preferred Equity | Market Comparable Technique | Comparable Multiple
Schedule of Investments [Line Items]
Assets Fair Value Disclosure		$ 31,950	$ 33,183
Preferred Equity | Market Comparable Technique | Minimum | Comparable Multiple
Schedule of Investments [Line Items]
Quantitative Information on Unobservable input		2.8	2.1
Preferred Equity | Market Comparable Technique | Maximum | Comparable Multiple
Schedule of Investments [Line Items]
Quantitative Information on Unobservable input		12.5	19.3
Preferred Equity | Market Comparable Technique | Weighted Average | Comparable Multiple
Schedule of Investments [Line Items]
Quantitative Information on Unobservable input	[1]	11.1	13.4
Preferred Equity | Option Pricing Model | Expected Volatility
Schedule of Investments [Line Items]
Assets Fair Value Disclosure			$ 1,961
Preferred Equity | Option Pricing Model | Minimum | Expected Volatility
Schedule of Investments [Line Items]
Quantitative Information on Unobservable input			0.900
Preferred Equity | Option Pricing Model | Maximum | Expected Volatility
Schedule of Investments [Line Items]
Quantitative Information on Unobservable input			0.900
Preferred Equity | Option Pricing Model | Weighted Average | Expected Volatility
Schedule of Investments [Line Items]
Quantitative Information on Unobservable input	[1]		0.900
Common Equity/Interests | Discounted Cash Flow | Discount Rate
Schedule of Investments [Line Items]
Assets Fair Value Disclosure			$ 111,446
Common Equity/Interests | Discounted Cash Flow | Minimum | Discount Rate
Schedule of Investments [Line Items]
Quantitative Information on Unobservable input			0.114
Common Equity/Interests | Discounted Cash Flow | Maximum | Discount Rate
Schedule of Investments [Line Items]
Quantitative Information on Unobservable input			0.114
Common Equity/Interests | Discounted Cash Flow | Weighted Average | Discount Rate
Schedule of Investments [Line Items]
Quantitative Information on Unobservable input	[1]		0.114
Common Equity/Interests | Recent Transaction | Recent Transaction
Schedule of Investments [Line Items]
Assets Fair Value Disclosure		$ 125	$ 4,256
Common Equity/Interests | Yield Analysis | Discount Rate
Schedule of Investments [Line Items]
Assets Fair Value Disclosure		$ 117,454	$ 449
Common Equity/Interests | Yield Analysis | Minimum | Discount Rate
Schedule of Investments [Line Items]
Quantitative Information on Unobservable input		0.135	0.125
Common Equity/Interests | Yield Analysis | Maximum | Discount Rate
Schedule of Investments [Line Items]
Quantitative Information on Unobservable input		0.143	0.125
Common Equity/Interests | Yield Analysis | Weighted Average | Discount Rate
Schedule of Investments [Line Items]
Quantitative Information on Unobservable input	[1]	0.143	0.125
Common Equity/Interests | Sale Proceeds | Sale Proceeds
Schedule of Investments [Line Items]
Assets Fair Value Disclosure			$ 20,977
Common Equity/Interests | Market Comparable Technique | Comparable Multiple
Schedule of Investments [Line Items]
Assets Fair Value Disclosure		$ 12,898	$ 11,996
Common Equity/Interests | Market Comparable Technique | Minimum | Comparable Multiple
Schedule of Investments [Line Items]
Quantitative Information on Unobservable input		3.6	6.5
Common Equity/Interests | Market Comparable Technique | Maximum | Comparable Multiple
Schedule of Investments [Line Items]
Quantitative Information on Unobservable input		26	36.5
Common Equity/Interests | Market Comparable Technique | Weighted Average | Comparable Multiple
Schedule of Investments [Line Items]
Quantitative Information on Unobservable input	[1]	11.8	13.3
Common Equity/Interests | Option Pricing Model | Expected Volatility
Schedule of Investments [Line Items]
Assets Fair Value Disclosure		$ 281	$ 190
Common Equity/Interests | Option Pricing Model | Minimum | Expected Volatility
Schedule of Investments [Line Items]
Quantitative Information on Unobservable input		0.30	0.350
Common Equity/Interests | Option Pricing Model | Maximum | Expected Volatility
Schedule of Investments [Line Items]
Quantitative Information on Unobservable input		1.15	0.900
Common Equity/Interests | Option Pricing Model | Weighted Average | Expected Volatility
Schedule of Investments [Line Items]
Quantitative Information on Unobservable input	[1]	0.591	0.350
Common Equity/Interests | Estimated Proceeds | Estimated Proceeds
Schedule of Investments [Line Items]
Assets Fair Value Disclosure		$ 21,369
Warrants - Warrants | Option Pricing Model | Expected Volatility
Schedule of Investments [Line Items]
Assets Fair Value Disclosure		$ 199	$ 474
Warrants - Warrants | Option Pricing Model | Minimum | Expected Volatility
Schedule of Investments [Line Items]
Quantitative Information on Unobservable input		0.50	0.500
Warrants - Warrants | Option Pricing Model | Maximum | Expected Volatility
Schedule of Investments [Line Items]
Quantitative Information on Unobservable input		0.50	0.500
Warrants - Warrants | Option Pricing Model | Weighted Average | Expected Volatility
Schedule of Investments [Line Items]
Quantitative Information on Unobservable input	[1]	0.50	0.500
Unsecured Debt | Recent Transaction | Recent Transaction
Schedule of Investments [Line Items]
Assets Fair Value Disclosure			$ 50

[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.