v3.25.1
Borrowings - Narrative (Details)
3 Months Ended
Feb. 12, 2025
USD ($)
Feb. 28, 2022
USD ($)
Mar. 01, 2021
USD ($)
Mar. 19, 2020
USD ($)
Mar. 31, 2025
USD ($)
Mar. 31, 2024
USD ($)
Dec. 31, 2024
USD ($)
Aug. 06, 2024
USD ($)
Aug. 05, 2024
USD ($)
Feb. 28, 2014
USD ($)
Debt Instrument [Line Items]                    
Maximum borrowing amount         $ 675,000,000   $ 695,000,000      
Long-term line of credit         5,000,000   5,000,000      
Deferred credit facility costs         3,500,000   3,904,000      
Credit facility, average outstanding borrowings         $ 5,000,000 $ 61,700,000        
Credit facility, average interest rate         8.31% 9.17%        
Assets         $ 734,837,000   763,040,000      
Debt fair value         369,734,000   387,995,000      
Asset Pledged as Collateral                    
Debt Instrument [Line Items]                    
Assets         323,900,000   332,000,000.0      
Asset Not Pledged as Collateral                    
Debt Instrument [Line Items]                    
Assets         410,900,000   431,000,000.0      
Unsecured Debt | 2025 Notes                    
Debt Instrument [Line Items]                    
Maximum borrowing amount         0   70,000,000      
Deferred credit facility costs             100,000      
Face amount       $ 70,000,000            
Interest rate       4.50%            
Repayments of debt       $ 70,000,000            
Asset coverage ratio, minimum 1.50                  
Interest coverage ratio, minimum 1.25                  
Minimum stockholders' equity balance $ 216,100,000                  
Upward adjustment, percent of issuance proceeds 65.00%                  
Debt fair value         0.0   70,300,000      
Unsecured Debt | 2026 Notes                    
Debt Instrument [Line Items]                    
Maximum borrowing amount         200,000,000   200,000,000      
Deferred credit facility costs         400,000   500,000      
Face amount     $ 200,000,000              
Interest rate     4.50%              
Debt fair value         195,200,000   194,800,000      
Aggregate principal balance, secured status threshold     $ 25,000,000              
Interest rate, below investment grade event     5.50%              
Debt term     5 years              
Unsecured Debt | 2027 Notes                    
Debt Instrument [Line Items]                    
Maximum borrowing amount         125,000,000   125,000,000      
Deferred credit facility costs         500,000   600,000      
Face amount   $ 125,000,000                
Interest rate   5.00%                
Debt fair value         119,900,000   119,000,000.0      
Aggregate principal balance, secured status threshold   $ 25,000,000                
Interest rate, below investment grade event   6.00%                
Debt term   5 years                
Unsecured Debt | 2028 Notes                    
Debt Instrument [Line Items]                    
Maximum borrowing amount         50,000,000   0      
Deferred credit facility costs         700,000          
Face amount $ 50,000,000                  
Interest rate 8.11%                  
Asset coverage ratio, minimum 1.50                  
Interest coverage ratio, minimum 1.25                  
Minimum stockholders' equity balance $ 236,776,000                  
Upward adjustment, percent of issuance proceeds 65.00%                  
Debt fair value         $ 51,200,000          
Aggregate principal balance, secured status threshold $ 25,000,000                  
Interest rate, below investment grade event 1.00%                  
Ratio calculation period 6 months                  
Debt term         3 years          
Revolving Credit Facility | Line of Credit                    
Debt Instrument [Line Items]                    
Maximum borrowing amount         $ 300,000,000   300,000,000 $ 300,000,000 $ 350,000,000 $ 150,000,000
Current borrowing capacity         300,000,000          
Accordion feature, higher borrowing capacity option         $ 400,000,000          
Debt instrument, variable interest rate, type flag         Secured Overnight Financing Rate (SOFR) [Member]          
Floor interest rate         0.50%          
Unused commitment fee percentage         0.50%          
Long-term line of credit         $ 5,000,000   5,000,000      
Deferred credit facility costs         3,500,000   3,900,000      
Debt fair value         $ 5,000,000   $ 5,000,000      
Revolving Credit Facility | Line of Credit | Maximum                    
Debt Instrument [Line Items]                    
Advance rate         50.00%          
Revolving Credit Facility | Line of Credit | Greater than or equal to 75%                    
Debt Instrument [Line Items]                    
Basis spread on variable rate         3.20%          
Facility utilization percentage         75.00%          
Revolving Credit Facility | Line of Credit | Greater than or equal to 50%                    
Debt Instrument [Line Items]                    
Basis spread on variable rate         3.35%          
Revolving Credit Facility | Line of Credit | Greater than or equal to 50% | Minimum                    
Debt Instrument [Line Items]                    
Facility utilization percentage         50.00%          
Revolving Credit Facility | Line of Credit | Greater than or equal to 50% | Maximum                    
Debt Instrument [Line Items]                    
Facility utilization percentage         75.00%          
Revolving Credit Facility | Line of Credit | Less than 50%                    
Debt Instrument [Line Items]                    
Basis spread on variable rate         3.50%          
Facility utilization percentage         50.00%          
Revolving Credit Facility | Line of Credit | During amortization period                    
Debt Instrument [Line Items]                    
Basis spread on variable rate         4.50%