v3.25.2
Borrowings - GBDC 3 2022-2 Debt Securitization (Narrative) (Details)
$ in Thousands
Jun. 03, 2024
USD ($)
Jun. 30, 2025
USD ($)
[1]
Sep. 30, 2024
USD ($)
portfolioCompany
Debt Instrument [Line Items]      
Investments, at fair value   $ 8,961,549 $ 8,235,411 [2]
GBDC 3 2022-2 Debt Securitization      
Debt Instrument [Line Items]      
Debt instrument, face amount $ 386,600    
Number of investment portfolio company | portfolioCompany     73
Investments, at fair value     $ 377,471
GBDC 3 2022-2 Debt Securitization | AAA Class A Senior Secured Floating Rate Notes Due 2034      
Debt Instrument [Line Items]      
Debt instrument, face amount $ 140,000    
Debt instrument, basis spread on variable rate 2.60%    
GBDC 3 2022-2 Debt Securitization | AA Class B Senior Secured Floating Rate Notes Due 2034      
Debt Instrument [Line Items]      
Debt instrument, face amount $ 38,800    
Debt instrument, basis spread on variable rate 3.09%    
GBDC 3 2022-2 Debt Securitization | AAA Class A Senior Secured Floating Rate Loans Due 2034      
Debt Instrument [Line Items]      
Debt instrument, face amount $ 85,000    
Debt instrument, basis spread on variable rate 2.60%    
GBDC 3 2022-2 Debt Securitization | Subordinated debt      
Debt Instrument [Line Items]      
Debt instrument, face amount $ 122,800    
[1] The fair values of investments were valued using significant unobservable inputs, unless noted otherwise. See Note 6.
[2] The fair values of investments were valued using significant unobservable inputs, unless noted otherwise. See Note 6.