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
 3 Months Ended
Mar. 31, 2025
Mar. 31, 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 (192,060) (173,036)
New Investments 245,984 291,299
Other 0 0
Ending balance 5,032,627 4,444,644
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 28,908 11,154
Investments | Net Unrealized Appreciation (Depreciation)    
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]    
Gain (loss) included in earnings 33,936 28,956
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 (179,192) (158,527)
New Investments 222,305 260,765
Other (27,250) 18,859
Ending balance 3,315,957 2,997,009
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 30,440 4,075
Debt | Net Unrealized Appreciation (Depreciation)    
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]    
Gain (loss) included in earnings (8,711) (12,080)
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 (12,868) (14,509)
New Investments 23,679 30,534
Other 27,250 (18,859)
Ending balance 1,694,787 1,441,125
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 (1,532) 7,079
Equity | Net Unrealized Appreciation (Depreciation)    
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]    
Gain (loss) included in earnings 37,887 41,136
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 0
Other 0 0
Ending balance 21,883 6,510
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 0
Equity Warrant | Net Unrealized Appreciation (Depreciation)    
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]    
Gain (loss) included in earnings $ 4,760 $ (100)