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Euro Deposits - Additional Information (Detail)
12 Months Ended
Dec. 31, 2020
USD ($)
Dec. 31, 2020
EUR (€)
Dec. 31, 2019
USD ($)
Dec. 31, 2019
EUR (€)
Dec. 31, 2020
EUR (€)
Dec. 31, 2019
EUR (€)
Cash And Cash Equivalents [Abstract]            
Annual nominal rate (0.50%)       (0.50%)  
Principal deposits $ 512,181,310 € 428,947,584 $ 276,072,032 € 261,604,378    
Principal redemptions 475,189,145 414,936,856 338,189,726 281,022,381    
Withdrawals (to pay expenses)   € 2,238,467   € 1,798,500    
Deposits, interest bearing $ 327,516,510   $ 287,480,505   € 267,879,731 € 256,107,470