v3.8.0.1
Investments - Offsetting of Financial Assets and Liabilities (Detail) - USD ($)
Sep. 30, 2017
Dec. 31, 2016
ProShares UltraShort Bloomberg Crude Oil [Member] | Swap Agreements [Member]    
Derivative [Line Items]    
Gross Amounts Offset in the Statements of Financial Condition $ 0 $ 0
Gross Amounts of Recognized Liabilities presented in the Statements of Financial Condition 13,678,377 12,206,881
Gross Amounts Offset in the Statements of Financial Condition 0 0
Net Amounts of Liabilities presented in the Statements of Financial Condition 13,678,377 12,206,881
ProShares UltraShort Gold [Member] | Forward Agreements [Member]    
Derivative [Line Items]    
Gross Amounts of Recognized Assets presented in the Statements of Financial Condition 2,961,605 3,033,566
Gross Amounts Offset in the Statements of Financial Condition 0 0
Net Amounts of Assets presented in the Statements of Financial Condition 2,961,605 3,033,566
Gross Amounts Offset in the Statements of Financial Condition 0 0
ProShares UltraShort Silver [Member] | Forward Agreements [Member]    
Derivative [Line Items]    
Gross Amounts of Recognized Assets presented in the Statements of Financial Condition 2,152,433 1,384,246
Gross Amounts Offset in the Statements of Financial Condition 0 0
Net Amounts of Assets presented in the Statements of Financial Condition 2,152,433 1,384,246
Gross Amounts Offset in the Statements of Financial Condition 0 0
ProShares UltraShort Euro [Member] | Foreign Currency Forward Contracts [Member]    
Derivative [Line Items]    
Gross Amounts of Recognized Assets presented in the Statements of Financial Condition 4,465,552 16,519,070
Gross Amounts Offset in the Statements of Financial Condition 0 0
Net Amounts of Assets presented in the Statements of Financial Condition 4,465,552 16,519,070
Gross Amounts of Recognized Liabilities presented in the Statements of Financial Condition 565,859 356,139
Gross Amounts Offset in the Statements of Financial Condition 0 0
Net Amounts of Liabilities presented in the Statements of Financial Condition 565,859 356,139
ProShares UltraShort Yen [Member] | Foreign Currency Forward Contracts [Member]    
Derivative [Line Items]    
Gross Amounts of Recognized Assets presented in the Statements of Financial Condition 9,817,020 16,870,357
Gross Amounts Offset in the Statements of Financial Condition 0 0
Net Amounts of Assets presented in the Statements of Financial Condition 9,817,020 16,870,357
Gross Amounts of Recognized Liabilities presented in the Statements of Financial Condition 570,141 125,420
Gross Amounts Offset in the Statements of Financial Condition 0 0
Net Amounts of Liabilities presented in the Statements of Financial Condition 570,141 125,420
ProShares Ultra Bloomberg Crude Oil [Member] | Swap Agreements [Member]    
Derivative [Line Items]    
Gross Amounts of Recognized Assets presented in the Statements of Financial Condition 40,796,900 55,358,571
Gross Amounts Offset in the Statements of Financial Condition 0 0
Net Amounts of Assets presented in the Statements of Financial Condition 40,796,900 55,358,571
Gross Amounts Offset in the Statements of Financial Condition 0 0
ProShares Ultra Gold [Member] | Forward Agreements [Member]    
Derivative [Line Items]    
Gross Amounts Offset in the Statements of Financial Condition 0 0
Gross Amounts of Recognized Liabilities presented in the Statements of Financial Condition 8,453,427 4,431,107
Gross Amounts Offset in the Statements of Financial Condition 0 0
Net Amounts of Liabilities presented in the Statements of Financial Condition 8,453,427 4,431,107
ProShares Ultra Silver [Member] | Forward Agreements [Member]    
Derivative [Line Items]    
Gross Amounts Offset in the Statements of Financial Condition 0 0
Gross Amounts of Recognized Liabilities presented in the Statements of Financial Condition 28,243,802 20,976,189
Gross Amounts Offset in the Statements of Financial Condition 0 0
Net Amounts of Liabilities presented in the Statements of Financial Condition 28,243,802 20,976,189
ProShares Ultra Euro [Member] | Foreign Currency Forward Contracts [Member]    
Derivative [Line Items]    
Gross Amounts of Recognized Assets presented in the Statements of Financial Condition 82,079 2,548
Gross Amounts Offset in the Statements of Financial Condition 0 0
Net Amounts of Assets presented in the Statements of Financial Condition 82,079 2,548
Gross Amounts of Recognized Liabilities presented in the Statements of Financial Condition 291,439 576,558
Gross Amounts Offset in the Statements of Financial Condition 0 0
Net Amounts of Liabilities presented in the Statements of Financial Condition 291,439 576,558
ProShares Ultra Yen [Member] | Foreign Currency Forward Contracts [Member]    
Derivative [Line Items]    
Gross Amounts of Recognized Assets presented in the Statements of Financial Condition 12,351 379
Gross Amounts Offset in the Statements of Financial Condition 0 0
Net Amounts of Assets presented in the Statements of Financial Condition 12,351 379
Gross Amounts of Recognized Liabilities presented in the Statements of Financial Condition 407,660 342,455
Gross Amounts Offset in the Statements of Financial Condition 0 0
Net Amounts of Liabilities presented in the Statements of Financial Condition $ 407,660 $ 342,455