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Significant Accounting Policies - Summary of Gold Receivable / Payable (Detail) - USD ($)
$ in Thousands
Jun. 30, 2022
Sep. 30, 2021
Schedule Of Significant Accounting Policies [Line Items]    
Gold receivable $ 0 $ 0
Gold payable 0 0
SPDR Gold Mini Shares Trust [Member]    
Schedule Of Significant Accounting Policies [Line Items]    
Gold receivable 0 0
Gold payable $ 0 $ 0