v3.26.1
N-2 - USD ($)
9 Months Ended
Jun. 30, 2026
Sep. 30, 2025
Jun. 30, 2025
Jun. 25, 2025
Feb. 14, 2025
Dec. 17, 2024
Nov. 05, 2024
Sep. 30, 2024
Cover [Abstract]                
Entity Central Index Key 0001901606              
Amendment Flag false              
Securities Act File Number 814-01505              
Document Type 10-Q              
Entity Registrant Name Golub Capital Direct Lending Unlevered Corporation              
Entity Address, Address Line One 200 Park Avenue              
Entity Address, Address Line Two 25th Floor              
Entity Address, City or Town New York              
Entity Address, State or Province NY              
Entity Address, Postal Zip Code 10166              
City Area Code 212              
Local Phone Number 750-6060              
Entity Emerging Growth Company true              
Entity Ex Transition Period true              
Financial Highlights [Abstract]                
Senior Securities Amount $ 0 $ 0            
General Description of Registrant [Abstract]                
Investment Objectives and Practices [Text Block]
Our investment objective is to generate current income and capital appreciation by investing primarily in one stop (a loan that combines characteristics of traditional first lien senior secured loans and second lien or subordinated loans and that are often referred to by other middle-market lenders as unitranche loans) and other senior secured loans of U.S. middle-market companies. We also selectively invest in second lien and subordinated loans of, and warrants and minority equity securities in U.S. middle-market companies. We intend to achieve our investment objective by (1) accessing the established loan origination channels developed by Golub Capital, a leading lender to U.S. middle-market companies with over $90.0 billion in capital under management(1) as of April 1, 2026, (2) selecting investments within our core middle-market company focus, (3) partnering with experienced private equity firms, or sponsors, in many cases with whom Golub Capital has invested alongside in the past, (4) implementing the disciplined underwriting standards of Golub Capital and (5) drawing upon the aggregate experience and resources of Golub Capital.
             
Risk Factors [Table Text Block] Risk Factors.There have been no material changes during the nine months ended June 30, 2026 to the risk factors discussed in Item 1A. Risk Factors in our Annual Report on Form 10-K for the year ended September 30, 2025.              
NAV Per Share $ 15.00 $ 15.00 $ 15.00 $ 15.00 $ 15.00 $ 15.00 $ 15.00 $ 15.00