Borrowings - Schedule of Carrying Values and Estimated Fair Values of Debt Instruments (Details) - Level 3 - Line of Credit - Revolving Credit Facility - USD ($) $ in Thousands	Dec. 31, 2024	Dec. 31, 2023
Carrying Amount
Debt Instrument [Line Items]
Long-term debt, fair value	$ 2,063,285	$ 322,000
Fair Value
Debt Instrument [Line Items]
Long-term debt, fair value	2,064,297	322,000
JPM Credit Facility \| Carrying Amount
Debt Instrument [Line Items]
Long-term debt, fair value	625,669	322,000
JPM Credit Facility \| Fair Value
Debt Instrument [Line Items]
Long-term debt, fair value	625,669	$ 322,000
JPM Revolver Facility \| Carrying Amount
Debt Instrument [Line Items]
Long-term debt, fair value	439,216
JPM Revolver Facility \| Fair Value
Debt Instrument [Line Items]
Long-term debt, fair value	439,216
Wells Fargo Credit Facility \| Carrying Amount
Debt Instrument [Line Items]
Long-term debt, fair value	300,000
Wells Fargo Credit Facility \| Fair Value
Debt Instrument [Line Items]
Long-term debt, fair value	300,000
2026 Notes \| Carrying Amount
Debt Instrument [Line Items]
Long-term debt, fair value	300,000
2026 Notes \| Fair Value
Debt Instrument [Line Items]
Long-term debt, fair value	291,444
2029 Notes \| Carrying Amount
Debt Instrument [Line Items]
Long-term debt, fair value	398,400
2029 Notes \| Fair Value
Debt Instrument [Line Items]
Long-term debt, fair value	$ 407,968

Franklin BSP Capital Corp 10-K