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FINANCIAL INSTRUMENTS, OFF-BALANCE SHEET RISKS AND CONTINGENCIES (Details) - USD ($)
Mar. 31, 2021
Dec. 31, 2020
United States Money Market Funds    
Loss Contingencies    
Deposits in domestic and foreign financial institutions, including cash investments in money market funds $ 1,947,534,000 $ 418,534,000
United States Treasury Obligations    
Loss Contingencies    
Deposits in domestic and foreign financial institutions, including cash investments in money market funds $ 838,557,523 $ 2,890,704,139