v3.26.1
Organization - Additional Information (Details) - USD ($)
$ / shares in Units, $ in Thousands
1 Months Ended 3 Months Ended 6 Months Ended 12 Months Ended
Mar. 31, 2026
Nov. 30, 2025
Oct. 31, 2025
Jul. 31, 2024
Oct. 31, 2021
Apr. 30, 2021
Mar. 31, 2021
Sep. 30, 2019
Mar. 31, 2026
Mar. 31, 2025
Mar. 31, 2026
Mar. 31, 2025
Sep. 30, 2025
Dec. 31, 2025
Oct. 29, 2025
Feb. 28, 2025
May 31, 2024
Apr. 30, 2023
Jan. 31, 2021
Debt Instrument [Line Items]                                      
Percentage of managed assets invested                     80.00%                
Notes payable to members $ 900               $ 900   $ 900   $ 0            
Net realized (gain) loss                     $ (6,079) $ 23,197              
Company acquired portfolio                           $ 250,000          
Debt securitization                             $ 21,000   $ 300,700 $ 297,800 $ 300,700
Sale of debt securitization     $ 21,000                                
Common stock shares issued                 0 11,562,000 0 18,838,000              
Public offering                 $ 0 $ 131,103 $ 0 $ 213,811              
Percentage of public offering price per notes issued 99.30%       101.50%   99.40%                        
At The Market Offering [Member]                                      
Debt Instrument [Line Items]                                      
Common stock shares issued                 0 11,562,000 0 18,838,000              
Weighted average price per share of common stock issued                   $ 11.34   $ 11.35              
Average Price Per Share Of Common Stock Issued                       $ 11.35              
Proceeds from issuance of common stock                   $ 131,000   $ 213,200              
Public offering                   $ 200 $ 192,200 $ 200 $ 192,200            
Legal and other offering costs $ 0     $ 500,000         $ 0   $ 0                
At The Market Offerings Terminated       250,000                              
Two Thousand Thirty One Asset Backed Debt [Member]                                      
Debt Instrument [Line Items]                                      
Debt securitization       351,000                              
Class D Notes                                      
Debt Instrument [Line Items]                                      
Sale of notes   $ 28,500                                  
2026 Notes Payable                                      
Debt Instrument [Line Items]                                      
Notes payable to members         $ 85,000   $ 100,000                        
Percentage of public offering price per notes issued         101.50%   99.40%                        
Debt instrument, interest rate                     4.25%                
Effective Interest Rate 4.15%               4.15%   4.15%                
Debt instrument, maturity date                     Apr. 01, 2026                
Debt instrument, periodic payment                       semiannually              
2029 Notes Payable                                      
Debt Instrument [Line Items]                                      
Notes payable to members $ 200,000               $ 200,000   $ 200,000                
Percentage of public offering price per notes issued 99.30%               99.30%   99.30%                
Debt instrument, interest rate                     6.75%                
Effective Interest Rate 7.00%               7.00%   7.00%                
PennantPark-TSO Senior Loan Fund, LP                                      
Debt Instrument [Line Items]                                      
Sale of investments to wholly owned subsidiary           $ 81,400                          
Sale of investments to wholly owned subsidiary in cash           69,500                          
Sale of investments to wholly owned subsidiary in equity interest           $ 11,900                          
Percentage of outstanding class A units           23.08%                          
Net realized (gain) loss           $ 400                          
First Lien Secured Debt | Minimum                                      
Debt Instrument [Line Items]                                      
Percentage of overall portfolio                     65.00%                
Second Lien Secured Debt | Maximum                                      
Debt Instrument [Line Items]                                      
Percentage of overall portfolio                     35.00%                
2031 Asset-Backed Debt                                      
Debt Instrument [Line Items]                                      
Debt securitization retained amount       $ 85,000                              
Percentage of preferred shares of securitization issuer               100.00%                      
2031 Asset-Backed Debt | Secured Overnight Financing Rate [Member]                                      
Debt Instrument [Line Items]                                      
Percentage points added to reference rate                     1.80%                
2031 Asset-Backed Debt | Class B-2 Senior Secured Fixed Rate Notes due 2031                                      
Debt Instrument [Line Items]                                      
Debt instrument, interest rate               4.30%                      
Debt instrument               $ 16,000                      
2031 Asset-Backed Debt | Class A1 Senior Secured Floating Rate Loans [Member]                                      
Debt Instrument [Line Items]                                      
Debt instrument               $ 78,500                      
Reference rate description                     three-month SOFR plus 1.8%                
2031 Asset-Backed Debt | Class D Secured Deferrable Floating Rate Notes                                      
Debt Instrument [Line Items]                                      
Percentage of notes issued by securitization issuer               100.00%                      
2037 Debt Securitization [Member]                                      
Debt Instrument [Line Items]                                      
Debt securitization retained amount                               $ 85,100      
2037 Debt Securitization [Member] | Class D Notes                                      
Debt Instrument [Line Items]                                      
Debt securitization retained amount                               28,500      
2037 Asset-Backed Debt                                      
Debt Instrument [Line Items]                                      
Debt securitization                               $ 474,600