v3.24.0.1
Borrowings - Schedule of Senior Securities Outstanding (Details) - USD ($)
 12 Months Ended
Dec. 31, 2023
Dec. 31, 2022
Dec. 31, 2021
Dec. 31, 2020
Dec. 31, 2019
Dec. 31, 2018
Dec. 31, 2017
Debt Instrument [Line Items]              
Amount outstanding $ 519,250,000 $ 559,250,000 $ 81,000,000 $ 99,000,000 $ 61,000,000 $ 59,500,000 $ 0
Asset Coverage per Unit 2,054,000 2,030,000 8,484,000 5,710,000 7,169,000 3,813,000  
2027 Senior Notes              
Debt Instrument [Line Items]              
Amount outstanding 152,250,000 152,250,000          
Asset Coverage per Unit 4,593,000 4,784,000          
2026 Senior Notes              
Debt Instrument [Line Items]              
Amount outstanding 95,000,000 70,000,000 20,000,000        
Asset Coverage per Unit 6,759,000 9,229,000 31,310,000        
Credit Facility              
Debt Instrument [Line Items]              
Amount outstanding 272,000,000 337,000,000 61,000,000 99,000,000 61,000,000    
Asset Coverage per Unit $ 3,011,000 $ 2,709,000 $ 10,938,000 $ 5,710,000 $ 7,169,000    
Credit Facility - CIBC              
Debt Instrument [Line Items]              
Amount outstanding           59,500,000  
Asset Coverage per Unit           $ 3,813,000