Fair Value Measurement - Summary of Changes in Fair Value of Level 3 Assets By Investment Type (Details) - USD ($) $ in Thousands		6 Months Ended
		Jun. 30, 2023	Jun. 30, 2022
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Net Change in Unrealized Appreciation (Depreciation) for assets still held		$ (10,909)	$ (41,127)
1st Lien/Senior Secured Debt
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Net Change in Unrealized Appreciation (Depreciation) for assets still held		(12,916)	(22,736)
1st Lien/Last-Out Unitranche
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Net Change in Unrealized Appreciation (Depreciation) for assets still held		(655)	(3,322)
2nd Lien/Senior Secured Debt
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Net Change in Unrealized Appreciation (Depreciation) for assets still held		(1,865)	(7,780)
Unsecured Debt
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Net Change in Unrealized Appreciation (Depreciation) for assets still held		(33)	(77)
Preferred Stock
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Net Change in Unrealized Appreciation (Depreciation) for assets still held		1,127	(4,846)
Common Stock
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Net Change in Unrealized Appreciation (Depreciation) for assets still held		3,593	(1,258)
Warrants
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Net Change in Unrealized Appreciation (Depreciation) for assets still held		(160)	(1,108)
Level 3
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Beginning Balance		3,341,847	3,270,660
Purchases	[1]	126,940	407,055
Net Realized Gain (Loss)		(39,582)	(7,106)
Net Change in Unrealized Appreciation (Depreciation)		28,432	(35,246)
Sales and Settlements	[2]	(73,673)	(254,013)
Net Amortization of Premium/Discount		10,280	17,052
Transfers In	[3]		50,220
Transfers Out	[3]	(34,201)
Ending Balance		3,360,043	3,448,622
Level 3 | 1st Lien/Senior Secured Debt
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Beginning Balance		3,050,929	2,843,010
Purchases	[1]	124,123	377,169
Net Realized Gain (Loss)		(3,274)	(5,176)
Net Change in Unrealized Appreciation (Depreciation)		(9,883)	(13,809)
Sales and Settlements	[2]	(73,468)	(144,958)
Net Amortization of Premium/Discount		9,089	11,056
Transfers Out	[3]	(34,201)
Ending Balance		3,063,315	3,067,292
Level 3 | 1st Lien/Last-Out Unitranche
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Beginning Balance		116,230	162,532
Purchases	[1]	1,182
Net Change in Unrealized Appreciation (Depreciation)		(655)	(5,341)
Sales and Settlements	[2]	(205)	(61,091)
Net Amortization of Premium/Discount		629	3,201
Ending Balance		117,181	99,301
Level 3 | 2nd Lien/Senior Secured Debt
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Beginning Balance		89,573	178,780
Purchases	[1]	391	14,819
Net Realized Gain (Loss)		(35,383)	(2,035)
Net Change in Unrealized Appreciation (Depreciation)		33,518	(8,807)
Sales and Settlements	[2]		(47,859)
Net Amortization of Premium/Discount		549	2,774
Transfers In	[3]		50,220
Ending Balance		88,648	187,892
Level 3 | Unsecured Debt
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Beginning Balance		7,630	1,733
Purchases	[1]	1,244	6,088
Net Change in Unrealized Appreciation (Depreciation)		(33)	(77)
Net Amortization of Premium/Discount		13	21
Ending Balance		8,854	7,765
Level 3 | Preferred Stock
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Beginning Balance		42,377	52,655
Net Realized Gain (Loss)		(42)
Net Change in Unrealized Appreciation (Depreciation)		1,169	(4,846)
Ending Balance		43,504	47,809
Level 3 | Common Stock
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Beginning Balance		34,497	30,100
Purchases	[1]		8,979
Net Realized Gain (Loss)		(883)	105
Net Change in Unrealized Appreciation (Depreciation)		4,476	(1,258)
Sales and Settlements	[2]		(105)
Ending Balance		38,090	37,821
Level 3 | Warrants
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Beginning Balance		611	1,850
Net Change in Unrealized Appreciation (Depreciation)		(160)	(1,108)
Ending Balance		$ 451	$ 742

[1] Purchases may include PIK, securities received in corporate actions and restructurings.

[2] Sales and Settlements may include securities delivered in corporate actions and restructuring of investments.

[3] Transfers in (out) of Level 3 are due to a decrease (increase) in the quantity and reliability of broker quotes obtained by the Investment Adviser.