v3.26.3
Portfolio Investments - Industries and Geographical Locations Comprising Greater than 10% of Portfolio Fair Value (Details) - USD ($)
$ in Thousands
 3 Months Ended 12 Months Ended
Sep. 30, 2026
Jun. 30, 2025
Jun. 30, 2026
Concentration Risk [Line Items]      
Cost $ 5,944,319   $ 6,315,369
Investments at fair value $ 5,944,478 [1]   6,342,558 [2]
Investments at Fair Value | Industry Concentration Risk      
Concentration Risk [Line Items]      
% of Portfolio 100.00% 100.00%  
Consumer Finance      
Concentration Risk [Line Items]      
Cost $ 775,068   760,592
Investments at fair value $ 1,164,510   1,149,153
Consumer Finance | Investments at Fair Value | Industry Concentration Risk      
Concentration Risk [Line Items]      
% of Portfolio 19.60% 18.10%  
Equity Real Estate Investment Trusts (REITs)      
Concentration Risk [Line Items]      
Cost $ 911,906   896,889
Investments at fair value $ 1,071,107   1,081,596
Equity Real Estate Investment Trusts (REITs) | Investments at Fair Value | Industry Concentration Risk      
Concentration Risk [Line Items]      
% of Portfolio 18.00% 17.10%  
Health Care Providers & Services      
Concentration Risk [Line Items]      
Cost $ 731,184   776,917
Investments at fair value $ 691,226   758,688
Health Care Providers & Services | Investments at Fair Value | Industry Concentration Risk      
Concentration Risk [Line Items]      
% of Portfolio 11.60% 12.00%  
All Other Industries      
Concentration Risk [Line Items]      
Cost $ 3,526,161   3,880,971
Investments at fair value $ 3,017,635   $ 3,353,121
All Other Industries | Investments at Fair Value | Industry Concentration Risk      
Concentration Risk [Line Items]      
% of Portfolio 50.80% 55.20%  
[1] Fair value is determined by or under the direction of our Board of Directors. Unless otherwise indicated by endnote 42 below, all of our investments are valued using significant unobservable inputs. In accordance with ASC 820, such investments are classified as Level 3 within the fair value hierarchy. See Notes 2 and 3 within the accompanying notes to consolidated financial statements for further discussion.
[2] Fair value is determined by or under the direction of our Board of Directors. Unless otherwise indicated by endnote 42 below, all of our investments are valued using significant unobservable inputs. In accordance with ASC 820, such investments are classified as Level 3 within the fair value hierarchy. See Notes 2 and 3 within the accompanying notes to consolidated financial statements for further discussion.