v3.26.3
Fair Value of Financial Instruments - Summary of Changes In Fair Value of Company's Level 3 Debt (Details) - USD ($)
 9 Months Ended 12 Months Ended
Sep. 30, 2026
Dec. 31, 2025
Fair Value Assets Measured On Recurring Basis Unobservable Input Reconciliation [Line Items]    
Transfers into/(out of) of Level 3 $ 0 $ 0
Significant Unobservable Inputs (Level 3)    
Fair Value Assets Measured On Recurring Basis Unobservable Input Reconciliation [Line Items]    
Fair Value, Beginning balance 2,386,232,000 1,710,169,000
Purchases, net of deferred fees 1,439,046,000 1,453,204,000
Fair value measurement with unobservable inputs reconciliation recurring basis asset co-investments funded on behalf of or directly by affiliate funds (106,355,000)  
Proceeds from sales and paydowns (1,001,807,000) (819,165,000)
Accretion of OID, EOT, and PIK payments 45,104,000 50,680,000
Net realized gain/(loss) $ (18,166,000) $ (64,114,000)
Fair Value, Asset, Recurring Basis, Unobservable Input Reconciliation, Gain (Loss), Statement of Income or Comprehensive Income [Extensible Enumeration] Realized gain Realized gain
Net change in unrealized appreciation/(depreciation) $ (3,976,000) $ 55,458,000
Fair Value, Ending balance 2,740,078,000 2,386,232,000
Net change in unrealized appreciation/(depreciation) on Level 3 investments still held (20,837,000) 16,840,000
Debt | Significant Unobservable Inputs (Level 3)    
Fair Value Assets Measured On Recurring Basis Unobservable Input Reconciliation [Line Items]    
Fair Value, Beginning balance 2,199,964,000 1,602,131,000
Purchases, net of deferred fees 1,387,122,000 1,396,567,000
Non-cash conversions (25,912,000) (4,640,000)
Fair value measurement with unobservable inputs reconciliation recurring basis asset co-investments funded on behalf of or directly by affiliate funds (104,968,000)  
Proceeds from sales and paydowns (981,410,000) (809,842,000)
Accretion of OID, EOT, and PIK payments 44,845,000 50,593,000
Net realized gain/(loss) (15,810,000) (62,262,000)
Net change in unrealized appreciation/(depreciation) (15,696,000) 27,417,000
Fair Value, Ending balance 2,488,135,000 2,199,964,000
Net change in unrealized appreciation/(depreciation) on Level 3 investments still held (25,905,000) (9,319,000)
Equity | Significant Unobservable Inputs (Level 3)    
Fair Value Assets Measured On Recurring Basis Unobservable Input Reconciliation [Line Items]    
Fair Value, Beginning balance 108,342,000 56,584,000
Purchases, net of deferred fees 43,961,000 36,056,000
Non-cash conversions 25,919,000 4,751,000
Fair value measurement with unobservable inputs reconciliation recurring basis asset co-investments funded on behalf of or directly by affiliate funds (740,000)  
Proceeds from sales and paydowns (15,529,000) (4,000,000)
Accretion of OID, EOT, and PIK payments 259,000 87,000
Net realized gain/(loss) (1,445,000) (679,000)
Net change in unrealized appreciation/(depreciation) 9,963,000 15,543,000
Fair Value, Ending balance 170,730,000 108,342,000
Net change in unrealized appreciation/(depreciation) on Level 3 investments still held 5,772,000 13,717,000
Warrants | Significant Unobservable Inputs (Level 3)    
Fair Value Assets Measured On Recurring Basis Unobservable Input Reconciliation [Line Items]    
Fair Value, Beginning balance 77,926,000 51,454,000
Purchases, net of deferred fees 7,963,000 20,581,000
Non-cash conversions (7,000) (111,000)
Fair value measurement with unobservable inputs reconciliation recurring basis asset co-investments funded on behalf of or directly by affiliate funds (647,000)  
Proceeds from sales and paydowns (4,868,000) (5,323,000)
Net realized gain/(loss) (911,000) (1,173,000)
Net change in unrealized appreciation/(depreciation) 1,757,000 12,498,000
Fair Value, Ending balance 81,213,000 77,926,000
Net change in unrealized appreciation/(depreciation) on Level 3 investments still held $ 704,000 $ 12,442,000