Quarterly report [Sections 13 or 15(d)]

FAIR VALUE HIERARCHY FOR INVESTMENTS???PORTFOLIO COMPOSITION - Schedule of Changes in Fair Value of Level??3 Portfolio Investments (Details)

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FAIR VALUE HIERARCHY FOR INVESTMENTS—PORTFOLIO COMPOSITION - Schedule of Changes in Fair Value of Level 3 Portfolio Investments (Details) - USD ($)
$ in Thousands
 9 Months Ended
Sep. 30, 2025
Sep. 30, 2024
Investments    
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]    
Beginning balance $ 4,932,669 $ 4,286,271
Transfers Out of Level 3 Hierarchy (16,810)  
Transfers Into Level 3 Hierarchy   0
Redemptions/ Repayments (788,769) (675,032)
New Investments 892,115 1,214,877
Other 0 0
Ending balance 5,129,440 4,911,054
Investments | Net Changes from Unrealized to Realized    
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]    
Gain (loss) included in earnings (10,479) (21,407)
Investments | Net Unrealized Appreciation (Depreciation)    
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]    
Gain (loss) included in earnings 120,714 106,345
Debt    
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]    
Beginning balance 3,278,365 2,883,917
Transfers Out of Level 3 Hierarchy 0  
Transfers Into Level 3 Hierarchy   0
Redemptions/ Repayments (740,766) (637,879)
New Investments 785,187 1,125,074
Other (37,295) 18,859
Ending balance 3,312,777 3,346,242
Debt | Net Changes from Unrealized to Realized    
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]    
Gain (loss) included in earnings 51,588 5,270
Debt | Net Unrealized Appreciation (Depreciation)    
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]    
Gain (loss) included in earnings (24,302) (48,999)
Equity    
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]    
Beginning balance 1,637,181 1,395,744
Transfers Out of Level 3 Hierarchy (16,810)  
Transfers Into Level 3 Hierarchy   0
Redemptions/ Repayments (48,003) (37,153)
New Investments 106,928 85,289
Other 37,295 (18,859)
Ending balance 1,787,450 1,557,019
Equity | Net Changes from Unrealized to Realized    
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]    
Gain (loss) included in earnings (62,067) (26,567)
Equity | Net Unrealized Appreciation (Depreciation)    
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]    
Gain (loss) included in earnings 132,926 158,565
Equity Warrant    
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]    
Beginning balance 17,123 6,610
Transfers Out of Level 3 Hierarchy 0  
Transfers Into Level 3 Hierarchy   0
Redemptions/ Repayments 0 0
New Investments 0 4,514
Other 0 0
Ending balance 29,213 7,793
Equity Warrant | Net Changes from Unrealized to Realized    
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]    
Gain (loss) included in earnings 0 (110)
Equity Warrant | Net Unrealized Appreciation (Depreciation)    
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]    
Gain (loss) included in earnings $ 12,090 $ (3,221)