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FINANCIAL INSTRUMENTS, OFF-BALANCE SHEET RISKS AND CONTINGENCIES (Details) - USD ($) | Dec. 31, 2019 | Dec. 31, 2018
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United States Money Market Funds |  |
Loss Contingencies |  |
Deposits in domestic and foreign financial institutions, including cash investments in money market funds | $ 20,000,000 | $ 52,000,000
United States Treasury Obligations |  |
Loss Contingencies |  |
Deposits in domestic and foreign financial institutions, including cash investments in money market funds | $ 1,156,245,411 | $ 1,604,935,976

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