Fair Value of Financial Instruments - Summary of Fair Value of Level 3 Investments and Ranges of Significant Unobservable Inputs Used to Value Level 3 Investments (Details) $ in Thousands	Sep. 30, 2022 USD ($)	Dec. 31, 2021 USD ($)
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis Valuation Techniques [Line Items]
Fair Value	$ 28,164	$ 57,960
Level 3
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis Valuation Techniques [Line Items]
Fair Value	1,205,625	1,105,680
Level 3 | Discounted Cash Flows
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis Valuation Techniques [Line Items]
Fair Value		5,620
Level 3 | Senior Secured First Lien
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis Valuation Techniques [Line Items]
Fair Value	312,283	268,851
Level 3 | Senior Secured First Lien | Discounted Cash Flows
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis Valuation Techniques [Line Items]
Fair Value	$ 228,748	$ 227,225
Level 3 | Senior Secured First Lien | Discounted Cash Flows | Discount Rate | Minimum
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis Valuation Techniques [Line Items]
Range	7.4	5.5
Level 3 | Senior Secured First Lien | Discounted Cash Flows | Discount Rate | Maximum
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis Valuation Techniques [Line Items]
Range	18.0	23.0
Level 3 | Senior Secured First Lien | Discounted Cash Flows | Discount Rate | Weighted Average
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis Valuation Techniques [Line Items]
Range	9.3	8.0
Level 3 | Senior Secured First Lien | Enterprise Value
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis Valuation Techniques [Line Items]
Fair Value	$ 5,677	$ 5,509
Level 3 | Senior Secured First Lien | Enterprise Value | Comparable EBITDA Multiple | Minimum
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis Valuation Techniques [Line Items]
Range	9.8	10.3
Level 3 | Senior Secured First Lien | Enterprise Value | Comparable EBITDA Multiple | Maximum
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis Valuation Techniques [Line Items]
Range	11.9	10.3
Level 3 | Senior Secured First Lien | Enterprise Value | Comparable EBITDA Multiple | Weighted Average
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis Valuation Techniques [Line Items]
Range	11.9	10.3
Level 3 | Senior Secured First Lien | Broker Quoted
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis Valuation Techniques [Line Items]
Fair Value	$ 77,858	$ 36,117
Level 3 | Unitranche First Lien
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis Valuation Techniques [Line Items]
Fair Value	775,226	711,296
Level 3 | Unitranche First Lien | Discounted Cash Flows
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis Valuation Techniques [Line Items]
Fair Value	$ 672,854	$ 665,759
Level 3 | Unitranche First Lien | Discounted Cash Flows | Discount Rate | Minimum
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis Valuation Techniques [Line Items]
Range	6.2	5.1
Level 3 | Unitranche First Lien | Discounted Cash Flows | Discount Rate | Maximum
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis Valuation Techniques [Line Items]
Range	14.7	10.4
Level 3 | Unitranche First Lien | Discounted Cash Flows | Discount Rate | Weighted Average
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis Valuation Techniques [Line Items]
Range	9.4	7.1
Level 3 | Unitranche First Lien | Enterprise Value
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis Valuation Techniques [Line Items]
Fair Value	$ 4,844
Level 3 | Unitranche First Lien | Enterprise Value | Comparable EBITDA Multiple | Minimum
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis Valuation Techniques [Line Items]
Range	6.0
Level 3 | Unitranche First Lien | Enterprise Value | Comparable EBITDA Multiple | Maximum
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis Valuation Techniques [Line Items]
Range	6.0
Level 3 | Unitranche First Lien | Enterprise Value | Comparable EBITDA Multiple | Weighted Average
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis Valuation Techniques [Line Items]
Range	6.0
Level 3 | Unitranche First Lien | Broker Quoted
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis Valuation Techniques [Line Items]
Fair Value	$ 97,528	$ 45,260
Level 3 | Unitranche First Lien | Collateral Analysis
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis Valuation Techniques [Line Items]
Fair Value		$ 277
Level 3 | Unitranche First Lien | Collateral Analysis | Recovery Rate
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis Valuation Techniques [Line Items]
Range		100.0
Level 3 | Unitranche First Lien Last Out
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis Valuation Techniques [Line Items]
Fair Value	13,149	$ 13,723
Level 3 | Unitranche First Lien Last Out | Discounted Cash Flows
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis Valuation Techniques [Line Items]
Fair Value	$ 11,064	$ 7,862
Level 3 | Unitranche First Lien Last Out | Discounted Cash Flows | Discount Rate | Minimum
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis Valuation Techniques [Line Items]
Range	6.9	6.5
Level 3 | Unitranche First Lien Last Out | Discounted Cash Flows | Discount Rate | Maximum
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis Valuation Techniques [Line Items]
Range	13.9	6.5
Level 3 | Unitranche First Lien Last Out | Discounted Cash Flows | Discount Rate | Weighted Average
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis Valuation Techniques [Line Items]
Range	(9.4)	6.5
Level 3 | Unitranche First Lien Last Out | Collateral Analysis
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis Valuation Techniques [Line Items]
Fair Value	$ 2,085	$ 5,861
Level 3 | Unitranche First Lien Last Out | Collateral Analysis | Recovery Rate
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis Valuation Techniques [Line Items]
Range	41.0	72.6
Level 3 | Senior Secured Second Lien
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis Valuation Techniques [Line Items]
Fair Value	$ 55,723	$ 47,584
Level 3 | Senior Secured Second Lien | Discounted Cash Flows
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis Valuation Techniques [Line Items]
Fair Value	$ 30,201	$ 47,295
Level 3 | Senior Secured Second Lien | Discounted Cash Flows | Discount Rate | Minimum
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis Valuation Techniques [Line Items]
Range	11.1	8.0
Level 3 | Senior Secured Second Lien | Discounted Cash Flows | Discount Rate | Maximum
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis Valuation Techniques [Line Items]
Range	16.3	21.7
Level 3 | Senior Secured Second Lien | Discounted Cash Flows | Discount Rate | Weighted Average
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis Valuation Techniques [Line Items]
Range	12.6	10.5
Level 3 | Senior Secured Second Lien | Enterprise Value
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis Valuation Techniques [Line Items]
Fair Value	$ 7,645
Level 3 | Senior Secured Second Lien | Enterprise Value | Comparable EBITDA Multiple | Minimum
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis Valuation Techniques [Line Items]
Range	8.0
Level 3 | Senior Secured Second Lien | Enterprise Value | Comparable EBITDA Multiple | Maximum
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis Valuation Techniques [Line Items]
Range	9.8
Level 3 | Senior Secured Second Lien | Enterprise Value | Comparable EBITDA Multiple | Weighted Average
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis Valuation Techniques [Line Items]
Range	8.6
Level 3 | Senior Secured Second Lien | Broker Quoted
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis Valuation Techniques [Line Items]
Fair Value	$ 17,877	$ 289
Level 3 | Unsecured Debt | Discounted Cash Flows
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis Valuation Techniques [Line Items]
Fair Value	$ 4,547
Level 3 | Unsecured Debt | Discounted Cash Flows | Discount Rate | Minimum
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis Valuation Techniques [Line Items]
Range	13.0	11.5
Level 3 | Unsecured Debt | Discounted Cash Flows | Discount Rate | Maximum
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis Valuation Techniques [Line Items]
Range	16.1	16.0
Level 3 | Unsecured Debt | Discounted Cash Flows | Discount Rate | Weighted Average
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis Valuation Techniques [Line Items]
Range	14.7	13.4
Level 3 | Equity & Other
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis Valuation Techniques [Line Items]
Fair Value		$ 58,606
Level 3 | Equity & Other | Enterprise Value
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis Valuation Techniques [Line Items]
Fair Value	$ 44,697	$ 57,279
Level 3 | Equity & Other | Enterprise Value | Comparable EBITDA Multiple | Minimum
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis Valuation Techniques [Line Items]
Range	10.7	6.3
Level 3 | Equity & Other | Enterprise Value | Comparable EBITDA Multiple | Maximum
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis Valuation Techniques [Line Items]
Range	28.1	32.4
Level 3 | Equity & Other | Enterprise Value | Comparable EBITDA Multiple | Weighted Average
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis Valuation Techniques [Line Items]
Range	15.6	9.8
Level 3 | Equity & Other | Broker Quoted
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis Valuation Techniques [Line Items]
Fair Value		$ 1,327