v2.4.0.8
Investments - Offsetting of Financial Assets and Liabilities (Detail) (USD $)
Mar. 31, 2014
Dec. 31, 2013
ProShares UltraShort DJ-UBS Commodity [Member] | Swap Agreements [Member]
   
Derivative [Line Items]    
Gross Amounts of Recognized Assets presented in the Statement of Financial Conditions $ 102,269   
Gross Amounts Offset in the Statement of Financial Conditions      
Net Amount 102,269   
Gross Amounts of Recognized Liabilities presented in the Statement of Financial Conditions    27,665
Gross Amounts Offset in the Statement of Financial Conditions      
Net Amount    27,665
ProShares UltraShort DJ-UBS Crude Oil [Member] | Swap Agreements [Member]
   
Derivative [Line Items]    
Gross Amounts of Recognized Assets presented in the Statement of Financial Conditions 71,219   
Gross Amounts Offset in the Statement of Financial Conditions      
Net Amount 71,219   
Gross Amounts of Recognized Liabilities presented in the Statement of Financial Conditions 764,150 2,332,900
Gross Amounts Offset in the Statement of Financial Conditions      
Net Amount 764,150 2,332,900
ProShares UltraShort DJ-UBS Crude Oil [Member] | VIX Futures Contracts [Member]
   
Derivative [Line Items]    
Gross Amounts of Recognized Assets presented in the Statement of Financial Conditions 345,825 1,503,943
Gross Amounts Offset in the Statement of Financial Conditions      
Net Amount 345,825 1,503,943
Gross Amounts of Recognized Liabilities presented in the Statement of Financial Conditions      
Gross Amounts Offset in the Statement of Financial Conditions      
Net Amount      
ProShares UltraShort DJ-UBS Natural Gas [Member] | VIX Futures Contracts [Member]
   
Derivative [Line Items]    
Gross Amounts of Recognized Assets presented in the Statement of Financial Conditions 2,752,495 1,520,548
Gross Amounts Offset in the Statement of Financial Conditions      
Net Amount 2,752,495 1,520,548
Gross Amounts of Recognized Liabilities presented in the Statement of Financial Conditions      
Gross Amounts Offset in the Statement of Financial Conditions      
Net Amount      
ProShares UltraShort Gold [Member] | VIX Futures Contracts [Member]
   
Derivative [Line Items]    
Gross Amounts of Recognized Assets presented in the Statement of Financial Conditions 2,100 300
Gross Amounts Offset in the Statement of Financial Conditions      
Net Amount 2,100 300
Gross Amounts of Recognized Liabilities presented in the Statement of Financial Conditions      
Gross Amounts Offset in the Statement of Financial Conditions      
Net Amount      
ProShares UltraShort Gold [Member] | Forward Agreements [Member]
   
Derivative [Line Items]    
Gross Amounts of Recognized Assets presented in the Statement of Financial Conditions 8,531,762 5,633,053
Gross Amounts Offset in the Statement of Financial Conditions      
Net Amount 8,531,762 5,633,053
Gross Amounts of Recognized Liabilities presented in the Statement of Financial Conditions      
Gross Amounts Offset in the Statement of Financial Conditions      
Net Amount      
ProShares UltraShort Silver [Member] | VIX Futures Contracts [Member]
   
Derivative [Line Items]    
Gross Amounts of Recognized Assets presented in the Statement of Financial Conditions    2,450
Gross Amounts Offset in the Statement of Financial Conditions      
Net Amount    2,450
Gross Amounts of Recognized Liabilities presented in the Statement of Financial Conditions 440   
Gross Amounts Offset in the Statement of Financial Conditions      
Net Amount 440   
ProShares UltraShort Silver [Member] | Forward Agreements [Member]
   
Derivative [Line Items]    
Gross Amounts of Recognized Assets presented in the Statement of Financial Conditions 7,742,580   
Gross Amounts Offset in the Statement of Financial Conditions      
Net Amount 7,742,580   
Gross Amounts of Recognized Liabilities presented in the Statement of Financial Conditions    2,227,857
Gross Amounts Offset in the Statement of Financial Conditions      
Net Amount    2,227,857
ProShares Short Euro [Member] | VIX Futures Contracts [Member]
   
Derivative [Line Items]    
Gross Amounts of Recognized Assets presented in the Statement of Financial Conditions    9,100
Gross Amounts Offset in the Statement of Financial Conditions      
Net Amount    9,100
Gross Amounts of Recognized Liabilities presented in the Statement of Financial Conditions 12,300   
Gross Amounts Offset in the Statement of Financial Conditions      
Net Amount 12,300   
ProShares UltraShort Australian Dollar [Member] | VIX Futures Contracts [Member]
   
Derivative [Line Items]    
Gross Amounts of Recognized Assets presented in the Statement of Financial Conditions      
Gross Amounts Offset in the Statement of Financial Conditions      
Net Amount      
Gross Amounts of Recognized Liabilities presented in the Statement of Financial Conditions 89,099 86,166
Gross Amounts Offset in the Statement of Financial Conditions      
Net Amount 89,099 86,166
ProShares UltraShort Euro [Member] | Foreign Currency Forward Contracts [Member]
   
Derivative [Line Items]    
Gross Amounts of Recognized Assets presented in the Statement of Financial Conditions    151,351
Gross Amounts Offset in the Statement of Financial Conditions      
Net Amount    151,351
Gross Amounts of Recognized Liabilities presented in the Statement of Financial Conditions 3,724,310 13,899,858
Gross Amounts Offset in the Statement of Financial Conditions      
Net Amount 3,724,310 13,899,858
ProShares UltraShort Yen [Member] | Foreign Currency Forward Contracts [Member]
   
Derivative [Line Items]    
Gross Amounts of Recognized Assets presented in the Statement of Financial Conditions 6,121,534 31,317,568
Gross Amounts Offset in the Statement of Financial Conditions      
Net Amount 6,121,534 31,317,568
Gross Amounts of Recognized Liabilities presented in the Statement of Financial Conditions 1,275,150 1,930,884
Gross Amounts Offset in the Statement of Financial Conditions      
Net Amount 1,275,150 1,930,884
ProShares Ultra DJ-UBS Commodity [Member] | Swap Agreements [Member]
   
Derivative [Line Items]    
Gross Amounts of Recognized Assets presented in the Statement of Financial Conditions    15,078
Gross Amounts Offset in the Statement of Financial Conditions      
Net Amount    15,078
Gross Amounts of Recognized Liabilities presented in the Statement of Financial Conditions 114,128   
Gross Amounts Offset in the Statement of Financial Conditions      
Net Amount 114,128   
ProShares Ultra DJ-UBS Crude Oil [Member] | Swap Agreements [Member]
   
Derivative [Line Items]    
Gross Amounts of Recognized Assets presented in the Statement of Financial Conditions 959,951 1,957,893
Gross Amounts Offset in the Statement of Financial Conditions      
Net Amount 959,951 1,957,893
Gross Amounts of Recognized Liabilities presented in the Statement of Financial Conditions      
Gross Amounts Offset in the Statement of Financial Conditions      
Net Amount      
ProShares Ultra DJ-UBS Crude Oil [Member] | VIX Futures Contracts [Member]
   
Derivative [Line Items]    
Gross Amounts of Recognized Assets presented in the Statement of Financial Conditions 121,862   
Gross Amounts Offset in the Statement of Financial Conditions      
Net Amount 121,862   
Gross Amounts of Recognized Liabilities presented in the Statement of Financial Conditions    997,210
Gross Amounts Offset in the Statement of Financial Conditions      
Net Amount    997,210
ProShares Ultra DJ-UBS Natural Gas [Member] | VIX Futures Contracts [Member]
   
Derivative [Line Items]    
Gross Amounts of Recognized Assets presented in the Statement of Financial Conditions      
Gross Amounts Offset in the Statement of Financial Conditions      
Net Amount      
Gross Amounts of Recognized Liabilities presented in the Statement of Financial Conditions 1,050,517 5,628,532
Gross Amounts Offset in the Statement of Financial Conditions      
Net Amount 1,050,517 5,628,532
ProShares Ultra Gold [Member] | VIX Futures Contracts [Member]
   
Derivative [Line Items]    
Gross Amounts of Recognized Assets presented in the Statement of Financial Conditions      
Gross Amounts Offset in the Statement of Financial Conditions      
Net Amount      
Gross Amounts of Recognized Liabilities presented in the Statement of Financial Conditions 2,200 300
Gross Amounts Offset in the Statement of Financial Conditions      
Net Amount 2,200 300
ProShares Ultra Gold [Member] | Forward Agreements [Member]
   
Derivative [Line Items]    
Gross Amounts of Recognized Assets presented in the Statement of Financial Conditions      
Gross Amounts Offset in the Statement of Financial Conditions      
Net Amount      
Gross Amounts of Recognized Liabilities presented in the Statement of Financial Conditions 12,010,072 6,812,974
Gross Amounts Offset in the Statement of Financial Conditions      
Net Amount 12,010,072 6,812,974
ProShares Ultra Silver [Member] | VIX Futures Contracts [Member]
   
Derivative [Line Items]    
Gross Amounts of Recognized Assets presented in the Statement of Financial Conditions      
Gross Amounts Offset in the Statement of Financial Conditions      
Net Amount      
Gross Amounts of Recognized Liabilities presented in the Statement of Financial Conditions 380 2,450
Gross Amounts Offset in the Statement of Financial Conditions      
Net Amount 380 2,450
ProShares Ultra Silver [Member] | Forward Agreements [Member]
   
Derivative [Line Items]    
Gross Amounts of Recognized Assets presented in the Statement of Financial Conditions      
Gross Amounts Offset in the Statement of Financial Conditions      
Net Amount      
Gross Amounts of Recognized Liabilities presented in the Statement of Financial Conditions 58,138,361 2,492,880
Gross Amounts Offset in the Statement of Financial Conditions      
Net Amount 58,138,361 2,492,880
ProShares Ultra Australian Dollar [Member] | VIX Futures Contracts [Member]
   
Derivative [Line Items]    
Gross Amounts of Recognized Assets presented in the Statement of Financial Conditions 13,503 10,650
Gross Amounts Offset in the Statement of Financial Conditions      
Net Amount 13,503 10,650
Gross Amounts of Recognized Liabilities presented in the Statement of Financial Conditions      
Gross Amounts Offset in the Statement of Financial Conditions      
Net Amount      
ProShares Ultra Euro [Member] | Foreign Currency Forward Contracts [Member]
   
Derivative [Line Items]    
Gross Amounts of Recognized Assets presented in the Statement of Financial Conditions 21,019 120,908
Gross Amounts Offset in the Statement of Financial Conditions      
Net Amount 21,019 120,908
Gross Amounts of Recognized Liabilities presented in the Statement of Financial Conditions 35 19,946
Gross Amounts Offset in the Statement of Financial Conditions      
Net Amount 35 19,946
ProShares Ultra Yen [Member] | Foreign Currency Forward Contracts [Member]
   
Derivative [Line Items]    
Gross Amounts of Recognized Assets presented in the Statement of Financial Conditions 1,004 4,052
Gross Amounts Offset in the Statement of Financial Conditions      
Net Amount 1,004 4,052
Gross Amounts of Recognized Liabilities presented in the Statement of Financial Conditions 42,233 163,361
Gross Amounts Offset in the Statement of Financial Conditions      
Net Amount 42,233 163,361
ProShares VIX Short-Term Futures ETF [Member] | VIX Futures Contracts [Member]
   
Derivative [Line Items]    
Gross Amounts of Recognized Assets presented in the Statement of Financial Conditions    3,179,017
Gross Amounts Offset in the Statement of Financial Conditions      
Net Amount    3,179,017
Gross Amounts of Recognized Liabilities presented in the Statement of Financial Conditions 3,088,786   
Gross Amounts Offset in the Statement of Financial Conditions      
Net Amount 3,088,786   
ProShares VIX Mid-Term Futures ETF [Member] | VIX Futures Contracts [Member]
   
Derivative [Line Items]    
Gross Amounts of Recognized Assets presented in the Statement of Financial Conditions    100,734
Gross Amounts Offset in the Statement of Financial Conditions      
Net Amount    100,734
Gross Amounts of Recognized Liabilities presented in the Statement of Financial Conditions 1,009,664   
Gross Amounts Offset in the Statement of Financial Conditions      
Net Amount 1,009,664   
ProShares Ultra VIX Short-Term Futures ETF [Member] | VIX Futures Contracts [Member]
   
Derivative [Line Items]    
Gross Amounts of Recognized Assets presented in the Statement of Financial Conditions      
Gross Amounts Offset in the Statement of Financial Conditions      
Net Amount      
Gross Amounts of Recognized Liabilities presented in the Statement of Financial Conditions 24,525,510 3,356,803
Gross Amounts Offset in the Statement of Financial Conditions      
Net Amount 24,525,510 3,356,803
ProShares Short VIX Short-Term Futures ETF [Member] | VIX Futures Contracts [Member]
   
Derivative [Line Items]    
Gross Amounts of Recognized Assets presented in the Statement of Financial Conditions 6,484,331 603,833
Gross Amounts Offset in the Statement of Financial Conditions      
Net Amount 6,484,331 603,833
Gross Amounts of Recognized Liabilities presented in the Statement of Financial Conditions      
Gross Amounts Offset in the Statement of Financial Conditions      
Net Amount