v3.25.2
Fair Value of Financial Instruments - Schedule of Investments at Amortized Cost and Fair Value (Details) - USD ($)
$ in Thousands
 6 Months Ended 12 Months Ended
Jun. 30, 2025
Dec. 31, 2024
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Investments at Amortized Cost $ 4,191,923 [1],[2],[3] $ 4,053,178 [4],[5],[6]
Investments at Fair Value $ 4,083,453 [1],[2],[3] $ 3,966,075 [4],[5],[6]
Investment Owned, At Fair Value | Investment Type Concentration Risk    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Fair Value Percentage of Total Portfolio 100.00% 100.00%
Senior Secured First Lien Debt    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Investments at Amortized Cost $ 3,205,469 $ 3,039,030
Investments at Fair Value $ 3,120,740 $ 2,965,692
Senior Secured First Lien Debt | Investment Owned, At Fair Value | Investment Type Concentration Risk    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Fair Value Percentage of Total Portfolio 76.30% 74.70%
Senior Secured Second Lien Debt    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Investments at Amortized Cost $ 153,060 $ 124,474
Investments at Fair Value $ 150,404 $ 121,927
Senior Secured Second Lien Debt | Investment Owned, At Fair Value | Investment Type Concentration Risk    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Fair Value Percentage of Total Portfolio 3.70% 3.10%
Subordinated Debt    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Investments at Amortized Cost $ 238,607 $ 202,212
Investments at Fair Value $ 232,792 $ 196,418
Subordinated Debt | Investment Owned, At Fair Value | Investment Type Concentration Risk    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Fair Value Percentage of Total Portfolio 5.70% 5.00%
Collateralized Securities    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Investments at Amortized Cost $ 7,911 $ 10,631
Investments at Fair Value $ 6,564 $ 10,893
Collateralized Securities | Investment Owned, At Fair Value | Investment Type Concentration Risk    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Fair Value Percentage of Total Portfolio 0.20% 0.30%
Equity/Other    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Investments at Amortized Cost $ 281,606 $ 271,397
Investments at Fair Value $ 268,019 $ 266,211
Equity/Other | Investment Owned, At Fair Value | Investment Type Concentration Risk    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Fair Value Percentage of Total Portfolio 6.60% 6.70%
FBLC Senior Loan Fund, LLC    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Investments at Amortized Cost $ 305,270 $ 405,434
Investments at Fair Value $ 304,934 $ 404,934
FBLC Senior Loan Fund, LLC | Investment Owned, At Fair Value | Investment Type Concentration Risk    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Fair Value Percentage of Total Portfolio 7.50% 10.20%
[1] Percentages are based on net assets attributable to common stock as of June 30, 2025.
[2] Unless otherwise indicated, all investments in the consolidated schedules of investments are non-affiliated, non-controlled investments.
[3] Unless otherwise indicated, all of the Company's investments or a portion thereof are pledged as collateral under the JPM Revolver Facility.
[4] Percentages are based on net assets attributable to common stock as of December 31, 2024.
[5] Unless otherwise indicated, all investments in the consolidated schedules of investments are non-affiliated, non-controlled investments.
[6] Unless otherwise indicated, all of the Company's investments or a portion thereof are pledged as collateral under the JPM Revolver Facility.