v3.26.1
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, 2026
Dec. 31, 2025
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Investments at Amortized Cost $ 4,177,726 [1],[2],[3] $ 4,178,354 [4],[5],[6]
Investments at Fair Value $ 4,079,384 [1],[2],[3] $ 4,071,008 [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 $ 3,188,484 $ 3,215,223
Investments at Fair Value $ 3,111,375 $ 3,136,374
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% 77.10%
Senior Secured Second Lien Debt    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Investments at Amortized Cost $ 159,318 $ 160,045
Investments at Fair Value $ 151,687 $ 152,406
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% 3.70%
Subordinated Debt    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Investments at Amortized Cost $ 287,806 $ 264,813
Investments at Fair Value $ 276,251 $ 259,132
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 6.80% 6.40%
Collateralized Securities    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Investments at Amortized Cost $ 7,432 $ 7,642
Investments at Fair Value $ 3,898 $ 4,861
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 0.10% 0.10%
Equity/Other    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Investments at Amortized Cost $ 309,525 $ 305,470
Investments at Fair Value $ 317,966 $ 293,279
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 7.80% 7.20%
FBLC Senior Loan Fund, LLC    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Investments at Amortized Cost $ 225,161 $ 225,161
Investments at Fair Value $ 218,207 $ 224,956
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 5.30% 5.50%
[1] Percentages are based on net assets attributable to common stock as of June 30, 2026.
[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, 2025.
[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 (as defined below).