v3.26.3
Borrowings - Narrative (Details)
1 Months Ended 3 Months Ended 9 Months Ended
Mar. 02, 2026
USD ($)
Feb. 27, 2026
USD ($)
Nov. 25, 2025
Feb. 12, 2025
USD ($)
Feb. 28, 2022
USD ($)
Mar. 31, 2026
USD ($)
Mar. 31, 2025
USD ($)
Sep. 30, 2026
USD ($)
Sep. 30, 2025
USD ($)
Sep. 30, 2026
USD ($)
Sep. 30, 2025
USD ($)
Dec. 31, 2025
USD ($)
Aug. 06, 2024
USD ($)
Aug. 05, 2024
USD ($)
Mar. 01, 2021
USD ($)
Mar. 19, 2020
USD ($)
Feb. 28, 2014
USD ($)
Debt Instrument [Line Items]                                  
Total Commitment               $ 550,000,000   $ 550,000,000   $ 675,000,000          
Outstanding borrowings under credit facility               150,000,000   150,000,000   95,000,000          
Deferred credit facility costs               3,695,000   3,695,000   4,643,000          
Credit facility, average outstanding borrowings               $ 167,600,000 $ 68,700,000 $ 166,800,000 $ 34,700,000            
Credit facility, average interest rate (in percentage)               7.02% 8.25% 7.06% 8.29%            
Assets               $ 749,649,000   $ 749,649,000   839,649,000          
Debt fair value               398,127,000   398,127,000   472,813,000          
Asset Pledged as Collateral                                  
Debt Instrument [Line Items]                                  
Assets               419,400,000   419,400,000   427,200,000          
Asset Not Pledged as Collateral                                  
Debt Instrument [Line Items]                                  
Assets               330,200,000   $ 330,200,000   412,500,000          
Unsecured Debt | 2025 Notes                                  
Debt Instrument [Line Items]                                  
Face amount                               $ 70,000,000.0  
Stated interest rate                               4.50%  
Repayments of debt             $ 70,000,000.0                    
Asset coverage ratio, minimum                   1.50              
Interest coverage ratio, minimum                   1.25              
Minimum stockholders' equity balance               216,100,000   $ 216,100,000              
Upward adjustment, issuance proceeds (in percentage)                   65.00%              
Unsecured Debt | 2026 Notes                                  
Debt Instrument [Line Items]                                  
Total Commitment               0   $ 0   200,000,000          
Face amount                             $ 200,000,000.0    
Stated interest rate                             4.50%    
Repayments of debt           $ 200,000,000.0                      
Debt fair value                       202,100,000          
Unsecured Debt | 2027 Notes                                  
Debt Instrument [Line Items]                                  
Total Commitment               125,000,000   125,000,000   125,000,000          
Face amount         $ 125,000,000.0                        
Stated interest rate         5.00%                        
Debt term         5 years                        
Debt fair value               124,000,000.0   124,000,000.0   124,200,000          
Aggregate principal balance, secured status threshold         $ 25,000,000                        
Interest rate, below investment grade event         6.00%                        
Unsecured Debt | 8.11% 2028 Notes                                  
Debt Instrument [Line Items]                                  
Total Commitment               $ 50,000,000   $ 50,000,000   50,000,000          
Face amount       $ 50,000,000.0                          
Stated interest rate       8.11%       8.11% 9.11% 8.11% 9.11%            
Asset coverage ratio, minimum       1.50                          
Interest coverage ratio, minimum       1.25                          
Minimum stockholders' equity balance       $ 236,776,000                          
Upward adjustment, issuance proceeds (in percentage)       65.00%                          
Debt term                   3 years              
Debt fair value               $ 50,300,000   $ 50,300,000   52,500,000          
Aggregate principal balance, secured status threshold       $ 25,000,000                          
Interest rate, below investment grade event       1.00%                          
Ratio calculation period       6 months                          
Unsecured Debt | 7.50% 2028 Notes                                  
Debt Instrument [Line Items]                                  
Total Commitment               75,000,000   75,000,000   0          
Deferred credit facility costs               $ 200,000   $ 200,000              
Face amount   $ 75,000,000.0                              
Stated interest rate   7.50%           7.50%   7.50%              
Repayments of debt $ 200,000,000.0                                
Asset coverage ratio, minimum   1.50                              
Minimum stockholders' equity balance   $ 230,800,000                              
Upward adjustment, issuance proceeds (in percentage)   25.00%                              
Debt term                   2 years              
Debt fair value               $ 74,600,000   $ 74,600,000              
Interest rate, below investment grade event   1.00%                              
Downward adjustment, issuance proceeds (in percentage)   25.00%                              
Interest rate, secured debt ratio event   1.50%                              
Interest rate, below investment grade and secured debt ratio event   2.00%                              
Payment in Kind (PIK) Note | 8.11% 2028 Notes                                  
Debt Instrument [Line Items]                                  
Ratio calculation period       6 months                          
Paid in kind interest to total interest       35.00%                          
Revolving Credit Facility | Line of Credit                                  
Debt Instrument [Line Items]                                  
Total Commitment               300,000,000   $ 300,000,000   300,000,000 $ 300,000,000 $ 350,000,000     $ 150,000,000.0
Debt instrument, variable interest rate, type flag     Secured Overnight Financing Rate (SOFR) [Member]             Secured Overnight Financing Rate (SOFR) [Member]              
Floor interest rate     0.50%             0.50%              
Current borrowing capacity               300,000,000   $ 300,000,000              
Accordion feature, higher borrowing capacity option               400,000,000   $ 400,000,000              
Unused commitment fee (in percentage)                   0.50%              
Outstanding borrowings under credit facility               150,000,000.0   $ 150,000,000.0   95,000,000.0          
Deferred credit facility costs               3,700,000   3,700,000   4,600,000          
Debt fair value               $ 150,000,000   $ 150,000,000   $ 95,000,000          
Revolving Credit Facility | Line of Credit | Maximum                                  
Debt Instrument [Line Items]                                  
Advance rate                   55.00%              
Revolving Credit Facility | Line of Credit | Greater than or equal to 75%                                  
Debt Instrument [Line Items]                                  
Basis spread on variable rate     2.75%             2.75%              
Facility utilization (in percentage)     75.00%             75.00%              
Revolving Credit Facility | Line of Credit | Greater than or equal to 50%                                  
Debt Instrument [Line Items]                                  
Basis spread on variable rate     2.85%             2.85%              
Revolving Credit Facility | Line of Credit | Greater than or equal to 50% | Minimum                                  
Debt Instrument [Line Items]                                  
Facility utilization (in percentage)     50.00%             50.00%              
Revolving Credit Facility | Line of Credit | Greater than or equal to 50% | Maximum                                  
Debt Instrument [Line Items]                                  
Facility utilization (in percentage)     75.00%             75.00%              
Revolving Credit Facility | Line of Credit | Less than 50%                                  
Debt Instrument [Line Items]                                  
Basis spread on variable rate     3.00%             3.00%              
Facility utilization (in percentage)     50.00%             50.00%              
Revolving Credit Facility | Line of Credit | During amortization period                                  
Debt Instrument [Line Items]                                  
Basis spread on variable rate     4.50%             4.50%