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Japanese Yen Deposits - Additional Information (Detail)
3 Months Ended 12 Months Ended
Mar. 31, 2021
USD ($)
Mar. 31, 2021
JPY (¥)
Mar. 31, 2020
USD ($)
Dec. 31, 2020
JPY (¥)
Mar. 31, 2021
JPY (¥)
Dec. 31, 2020
USD ($)
Dec. 31, 2020
JPY (¥)
Cash And Cash Equivalents [Abstract]              
Proceeds from purchases of redeemable capital Shares $ 4,541,369 ¥ 472,007,223 $ 114,055,410 ¥ 24,652,512,877      
Principal redemptions 48,242,779 5,188,351,618 $ 59,642,260 19,901,290,156      
Withdrawals (to pay expenses)   ¥ 37,531,007   ¥ 153,028,653      
Deposits, interest bearing $ 187,811,702       ¥ 20,753,193,055 $ 247,053,789 ¥ 25,507,068,457
Annual nominal rate (0.20%)       (0.20%)