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Euro Deposits - Additional Information (Detail)
6 Months Ended 12 Months Ended
Jun. 30, 2021
USD ($)
Jun. 30, 2021
EUR (€)
Jun. 30, 2020
USD ($)
Dec. 31, 2020
EUR (€)
Jun. 30, 2021
EUR (€)
Dec. 31, 2020
USD ($)
Dec. 31, 2020
EUR (€)
Cash And Cash Equivalents [Abstract]              
Annual nominal rate (0.65%)       (0.65%)    
Principal deposits $ 113,462,451 € 93,761,912 $ 124,290,283 € 428,947,584      
Principal redemptions 135,478,655 112,503,301 $ 198,102,363 414,936,856      
Withdrawals (to pay expenses)   € 1,244,359   € 2,238,467      
Deposits, interest bearing $ 293,977,273       € 247,893,983 $ 327,764,221 € 267,879,731