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Australian Dollar Deposits - Additional Information (Detail)
3 Months Ended 12 Months Ended
Mar. 31, 2020
USD ($)
Mar. 31, 2020
AUD ($)
Mar. 31, 2019
USD ($)
Dec. 31, 2019
AUD ($)
Mar. 31, 2020
AUD ($)
Dec. 31, 2019
USD ($)
Dec. 31, 2019
AUD ($)
Cash And Cash Equivalents [Abstract]              
Annual nominal rate (0.15%)       (0.15%)    
Principal deposits   $ 0 $ 7,094,912 $ 20,000,018      
Principal redemptions $ 10,543,357 0 $ 17,792,563 54,998,678      
Withdrawals (to pay expenses)   $ 0   $ 11,848      
Deposits, interest bearing $ 79,560,090       $ 129,989,492 $ 91,376,174 $ 129,989,492