v2.4.0.8
Investments - Fair Value of Derivative Instruments (Detail) (USD $)
Jun. 30, 2014
Dec. 31, 2013
Derivative Instruments, Gain (Loss) [Line Items]    
Derivative asset not designated as hedging instrument, Unrealized Appreciation $ 117,759,823 $ 49,932,144
Derivative liability not designated as hedging instrument, Unrealized Depreciation 111,091,407 80,537,134
Commodity Contracts [Member] | Payable on Open Futures Contracts, Unrealized Depreciation on Swap and/or Forward Agreements [Member] | ProShares UltraShort Bloomberg Commodity [Member]
   
Derivative Instruments, Gain (Loss) [Line Items]    
Derivative liability not designated as hedging instrument, Unrealized Depreciation 49,719 27,665
Commodity Contracts [Member] | Payable on Open Futures Contracts, Unrealized Depreciation on Swap and/or Forward Agreements [Member] | ProShares UltraShort Bloomberg Crude Oil [Member]
   
Derivative Instruments, Gain (Loss) [Line Items]    
Derivative liability not designated as hedging instrument, Unrealized Depreciation 21,273,793 3,565,673
Commodity Contracts [Member] | Payable on Open Futures Contracts, Unrealized Depreciation on Swap and/or Forward Agreements [Member] | ProShares UltraShort Silver [Member]
   
Derivative Instruments, Gain (Loss) [Line Items]    
Derivative liability not designated as hedging instrument, Unrealized Depreciation 10,580,123 2,227,857
Commodity Contracts [Member] | Payable on Open Futures Contracts, Unrealized Depreciation on Swap and/or Forward Agreements [Member] | ProShares Ultra Bloomberg Natural Gas [Member]
   
Derivative Instruments, Gain (Loss) [Line Items]    
Derivative liability not designated as hedging instrument, Unrealized Depreciation 1,410,765 3,656,539
Commodity Contracts [Member] | Payable on Open Futures Contracts, Unrealized Depreciation on Swap and/or Forward Agreements [Member] | ProShares Ultra Gold [Member]
   
Derivative Instruments, Gain (Loss) [Line Items]    
Derivative liability not designated as hedging instrument, Unrealized Depreciation   6,827,534
Commodity Contracts [Member] | Payable on Open Futures Contracts, Unrealized Depreciation on Swap and/or Forward Agreements [Member] | ProShares Ultra Silver [Member]
   
Derivative Instruments, Gain (Loss) [Line Items]    
Derivative liability not designated as hedging instrument, Unrealized Depreciation   2,507,080
Commodity Contracts [Member] | Payable on Open Futures Contracts, Unrealized Depreciation on Swap and/or Forward Agreements [Member] | ProShares UltraShort Gold [Member]
   
Derivative Instruments, Gain (Loss) [Line Items]    
Derivative liability not designated as hedging instrument, Unrealized Depreciation 10,588,348  
Commodity Contracts [Member] | Payable on Open Futures Contracts, Unrealized Depreciation on Swap and/or Forward Agreements [Member] | ProShares Ultra Bloomberg Commodity [Member]
   
Derivative Instruments, Gain (Loss) [Line Items]    
Derivative liability not designated as hedging instrument, Unrealized Depreciation 5,077  
Commodity Contracts [Member] | Receivables on Open Futures Contracts, Unrealized Appreciation on Swap and/ or Forwards Agreements [Member] | ProShares UltraShort Silver [Member]
   
Derivative Instruments, Gain (Loss) [Line Items]    
Derivative asset not designated as hedging instrument, Unrealized Appreciation   14,200
Commodity Contracts [Member] | Receivables on Open Futures Contracts, Unrealized Appreciation on Swap and/ or Forwards Agreements [Member] | ProShares Ultra Gold [Member]
   
Derivative Instruments, Gain (Loss) [Line Items]    
Derivative asset not designated as hedging instrument, Unrealized Appreciation 13,232,735  
Commodity Contracts [Member] | Receivables on Open Futures Contracts, Unrealized Appreciation on Swap and/ or Forwards Agreements [Member] | ProShares Ultra Silver [Member]
   
Derivative Instruments, Gain (Loss) [Line Items]    
Derivative asset not designated as hedging instrument, Unrealized Appreciation 86,910,666  
Commodity Contracts [Member] | Receivables on Open Futures Contracts, Unrealized Appreciation on Swap and/ or Forwards Agreements [Member] | ProShares UltraShort Gold [Member]
   
Derivative Instruments, Gain (Loss) [Line Items]    
Derivative asset not designated as hedging instrument, Unrealized Appreciation   5,647,573
Commodity Contracts [Member] | Receivables on Open Futures Contracts, Unrealized Appreciation on Swap and/ or Forwards Agreements [Member] | ProShares Ultra Bloomberg Commodity [Member]
   
Derivative Instruments, Gain (Loss) [Line Items]    
Derivative asset not designated as hedging instrument, Unrealized Appreciation 14,121 15,078
Commodity Contracts [Member] | Receivables on Open Futures Contracts, Unrealized Appreciation on Swap and/ or Forwards Agreements [Member] | ProShares UltraShort Bloomberg Natural Gas [Member]
   
Derivative Instruments, Gain (Loss) [Line Items]    
Derivative asset not designated as hedging instrument, Unrealized Appreciation 2,467,844 1,042,300
Commodity Contracts [Member] | Receivables on Open Futures Contracts, Unrealized Appreciation on Swap and/ or Forwards Agreements [Member] | ProShares Ultra Bloomberg Crude Oil [Member]
   
Derivative Instruments, Gain (Loss) [Line Items]    
Derivative asset not designated as hedging instrument, Unrealized Appreciation 5,234,134 2,584,554
Foreign Exchange Contracts [Member] | Unrealized Depreciation on Foreign Currency Forward Contracts and Payable on Open Futures Contracts [Member] | ProShares Short Euro [Member]
   
Derivative Instruments, Gain (Loss) [Line Items]    
Derivative liability not designated as hedging instrument, Unrealized Depreciation 111,159 33,231
Foreign Exchange Contracts [Member] | Unrealized Depreciation on Foreign Currency Forward Contracts and Payable on Open Futures Contracts [Member] | ProShares UltraShort Euro [Member]
   
Derivative Instruments, Gain (Loss) [Line Items]    
Derivative liability not designated as hedging instrument, Unrealized Depreciation 5,915,312 13,899,858
Foreign Exchange Contracts [Member] | Unrealized Depreciation on Foreign Currency Forward Contracts and Payable on Open Futures Contracts [Member] | ProShares UltraShort Yen [Member]
   
Derivative Instruments, Gain (Loss) [Line Items]    
Derivative liability not designated as hedging instrument, Unrealized Depreciation 10,127,815 1,930,884
Foreign Exchange Contracts [Member] | Unrealized Depreciation on Foreign Currency Forward Contracts and Payable on Open Futures Contracts [Member] | ProShares Ultra Australian Dollar [Member]
   
Derivative Instruments, Gain (Loss) [Line Items]    
Derivative liability not designated as hedging instrument, Unrealized Depreciation   118,220
Foreign Exchange Contracts [Member] | Unrealized Depreciation on Foreign Currency Forward Contracts and Payable on Open Futures Contracts [Member] | ProShares Ultra Euro [Member]
   
Derivative Instruments, Gain (Loss) [Line Items]    
Derivative liability not designated as hedging instrument, Unrealized Depreciation 378 19,946
Foreign Exchange Contracts [Member] | Unrealized Depreciation on Foreign Currency Forward Contracts and Payable on Open Futures Contracts [Member] | ProShares Ultra Yen [Member]
   
Derivative Instruments, Gain (Loss) [Line Items]    
Derivative liability not designated as hedging instrument, Unrealized Depreciation 24,196 163,361
Foreign Exchange Contracts [Member] | Unrealized Depreciation on Foreign Currency Forward Contracts and Payable on Open Futures Contracts [Member] | ProShares UltraShort Australian Dollar [Member]
   
Derivative Instruments, Gain (Loss) [Line Items]    
Derivative liability not designated as hedging instrument, Unrealized Depreciation 362,840  
Foreign Exchange Contracts [Member] | Unrealized Appreciation on Foreign Currency Forward Contracts and Receivables on Open Futures Contracts [Member] | ProShares UltraShort Euro [Member]
   
Derivative Instruments, Gain (Loss) [Line Items]    
Derivative asset not designated as hedging instrument, Unrealized Appreciation 327,971 151,351
Foreign Exchange Contracts [Member] | Unrealized Appreciation on Foreign Currency Forward Contracts and Receivables on Open Futures Contracts [Member] | ProShares UltraShort Yen [Member]
   
Derivative Instruments, Gain (Loss) [Line Items]    
Derivative asset not designated as hedging instrument, Unrealized Appreciation 480,205 31,317,568
Foreign Exchange Contracts [Member] | Unrealized Appreciation on Foreign Currency Forward Contracts and Receivables on Open Futures Contracts [Member] | ProShares Ultra Australian Dollar [Member]
   
Derivative Instruments, Gain (Loss) [Line Items]    
Derivative asset not designated as hedging instrument, Unrealized Appreciation 63,500  
Foreign Exchange Contracts [Member] | Unrealized Appreciation on Foreign Currency Forward Contracts and Receivables on Open Futures Contracts [Member] | ProShares Ultra Euro [Member]
   
Derivative Instruments, Gain (Loss) [Line Items]    
Derivative asset not designated as hedging instrument, Unrealized Appreciation 31,105 120,908
Foreign Exchange Contracts [Member] | Unrealized Appreciation on Foreign Currency Forward Contracts and Receivables on Open Futures Contracts [Member] | ProShares Ultra Yen [Member]
   
Derivative Instruments, Gain (Loss) [Line Items]    
Derivative asset not designated as hedging instrument, Unrealized Appreciation 76,915 4,052
Foreign Exchange Contracts [Member] | Unrealized Appreciation on Foreign Currency Forward Contracts and Receivables on Open Futures Contracts [Member] | ProShares UltraShort Australian Dollar [Member]
   
Derivative Instruments, Gain (Loss) [Line Items]    
Derivative asset not designated as hedging instrument, Unrealized Appreciation   917,605
VIX Futures Contracts [Member] | Payable on Open Futures Contracts and Unrealized Depreciation on Swap Agreements [Member] | ProShares VIX Short-Term Futures ETF [Member]
   
Derivative Instruments, Gain (Loss) [Line Items]    
Derivative liability not designated as hedging instrument, Unrealized Depreciation 6,613,486 16,652,686
VIX Futures Contracts [Member] | Payable on Open Futures Contracts and Unrealized Depreciation on Swap Agreements [Member] | ProShares VIX Mid-Term Futures ETF [Member]
   
Derivative Instruments, Gain (Loss) [Line Items]    
Derivative liability not designated as hedging instrument, Unrealized Depreciation 3,495,050 4,896,689
VIX Futures Contracts [Member] | Payable on Open Futures Contracts and Unrealized Depreciation on Swap Agreements [Member] | ProShares Ultra VIX Short-Term Futures ETF [Member]
   
Derivative Instruments, Gain (Loss) [Line Items]    
Derivative liability not designated as hedging instrument, Unrealized Depreciation 40,533,346 24,009,911
VIX Futures Contracts [Member] | Receivables on Open Futures Contracts and Unrealized Appreciation on Swap Agreements [Member] | ProShares Short VIX Short-Term Futures ETF [Member]
   
Derivative Instruments, Gain (Loss) [Line Items]    
Derivative asset not designated as hedging instrument, Unrealized Appreciation $ 8,920,627 $ 8,116,955