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Australian Dollar Deposits - Additional Information (Detail)
2 Months Ended 12 Months Ended
Dec. 31, 2018
USD ($)
Dec. 31, 2018
AUD ($)
Dec. 31, 2019
USD ($)
Dec. 31, 2019
AUD ($)
Oct. 31, 2018
USD ($)
Dec. 31, 2019
AUD ($)
Dec. 31, 2018
AUD ($)
Cash And Cash Equivalents [Abstract]              
Annual nominal rate     0.00%     0.00%  
Principal deposits $ 7,287,860 $ 10,000,000 $ 14,241,193 $ 20,000,018 $ 18,880,911    
Principal redemptions 10,854,234 $ 15,000,000 28,225,546 54,998,678 $ 30,200,732    
Withdrawals (to pay expenses)       $ 11,848      
Deposits, interest bearing $ 116,159,963   $ 91,376,174     $ 129,989,492 $ 165,000,000