Quarterly report [Sections 13 or 15(d)]

Fair Value of Financial Instruments - Summary of Reconciliation of Changes for All Financial Assets and Liabilities Measured at Fair Value on Recurring Basis (Details)

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Fair Value of Financial Instruments - Summary of Reconciliation of Changes for All Financial Assets and Liabilities Measured at Fair Value on Recurring Basis (Details) - Significant Unobservable Inputs (Level 3) - Recurring - USD ($)
$ in Thousands
 9 Months Ended
Sep. 30, 2025
Sep. 30, 2024
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]    
Beginning balance $ 3,613,959 $ 3,185,103
Net realized gains (losses) (54,913) (11,561)
Net change in unrealized appreciation (depreciation) 42,920 (39,187)
Purchases 1,402,454 1,111,555
Sales (74,392) (21,326)
Repayments (690,976) (732,225)
Gross transfers into Level 3 22,558 2,323
Gross transfers out of Level 3 (22,558) (2,323)
Ending balance 4,239,052 3,492,359
Accounts payable and accrued liabilities    
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]    
Beginning balance (1,012)  
Net realized gain (loss) (568)  
Net change in unrealized appreciation (depreciation) 1,534  
Purchases 2,003  
Sales (1,991)  
Gross transfers into Level 3   (1,770)
Ending balance (34) (1,770)
Preferred Stock    
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]    
Beginning balance 53,802 53,038
Net realized gains (losses)   (711)
Net change in unrealized appreciation (depreciation) (6,309) (9,013)
Purchases 4,329 1,597
Gross transfers into Level 3   2,431
Ending balance 51,822 47,342
Common Stock    
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]    
Beginning balance 44,593 41,790
Net realized gains (losses) (645) (1,351)
Net change in unrealized appreciation (depreciation) 2,969 474
Purchases 975 4,100
Sales (1,606)  
Gross transfers into Level 3 22,558 1,662
Gross transfers out of Level 3 (5,094)  
Ending balance 63,750 46,675
Warrants    
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]    
Beginning balance 21,823 22,088
Net realized gains (losses) 607 (464)
Net change in unrealized appreciation (depreciation) 1,419 (2,367)
Purchases 5,372 2,948
Sales (1,410) (2,829)
Ending balance 27,811 19,376
Senior Secured Debt    
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]    
Beginning balance 3,419,044 2,987,577
Net realized gains (losses) (54,380) (9,120)
Net change in unrealized appreciation (depreciation) 42,790 (34,978)
Purchases 1,383,694 1,099,563
Sales (67,521)  
Repayments (690,976) (732,225)
Gross transfers out of Level 3 (5,242) (4,093)
Ending balance 4,027,409 3,306,724
Unsecured Debt    
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]    
Beginning balance 75,557 69,722
Net change in unrealized appreciation (depreciation) 547 828
Purchases 4,267 3,304
Gross transfers out of Level 3 (12,222)  
Ending balance 68,149 73,854
Escrow Receivables    
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]    
Beginning balance 152  
Net realized gains (losses) 73  
Net change in unrealized appreciation (depreciation) (30)  
Purchases 1,814  
Sales (1,864)  
Ending balance $ 145  
Escrow and Other Investment Receivables    
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]    
Beginning balance   10,888
Net realized gains (losses)   85
Net change in unrealized appreciation (depreciation)   5,869
Purchases   43
Sales   (18,497)
Gross transfers out of Level 3   1,770
Ending balance   $ 158