v2.4.0.8
Investments - Fair Value of Derivative Instruments (Detail) (USD $)
Mar. 31, 2014
Dec. 31, 2013
Derivative Instruments, Gain (Loss) [Line Items]    
Derivative asset not designated as hedging instrument, Unrealized Appreciation $ 38,486,246 $ 49,932,144
Derivative liability not designated as hedging instrument, Unrealized Depreciation 122,164,235 80,537,134
Commodity Contracts [Member] | Receivables on Open Futures Contracts, Unrealized Appreciation on Swap and/ or Forwards Agreements [Member] | ProShares UltraShort DJ-UBS Commodity [Member]
   
Derivative Instruments, Gain (Loss) [Line Items]    
Derivative asset not designated as hedging instrument, Unrealized Appreciation 102,269  
Commodity Contracts [Member] | Receivables on Open Futures Contracts, Unrealized Appreciation on Swap and/ or Forwards Agreements [Member] | ProShares UltraShort DJ-UBS Crude Oil [Member]
   
Derivative Instruments, Gain (Loss) [Line Items]    
Derivative asset not designated as hedging instrument, Unrealized Appreciation 71,219  
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 8,548,622 5,647,573
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 7,747,910 14,200
Commodity Contracts [Member] | Receivables on Open Futures Contracts, Unrealized Appreciation on Swap and/ or Forwards Agreements [Member] | ProShares Ultra DJ-UBS Commodity [Member]
   
Derivative Instruments, Gain (Loss) [Line Items]    
Derivative asset not designated as hedging instrument, Unrealized Appreciation   15,078
Commodity Contracts [Member] | Receivables on Open Futures Contracts, Unrealized Appreciation on Swap and/ or Forwards Agreements [Member] | ProShares Ultra DJ-UBS Crude Oil [Member]
   
Derivative Instruments, Gain (Loss) [Line Items]    
Derivative asset not designated as hedging instrument, Unrealized Appreciation 3,069,265 2,584,554
Commodity Contracts [Member] | Receivables on Open Futures Contracts, Unrealized Appreciation on Swap and/ or Forwards Agreements [Member] | ProShares UltraShort DJ-UBS Natural Gas [Member]
   
Derivative Instruments, Gain (Loss) [Line Items]    
Derivative asset not designated as hedging instrument, Unrealized Appreciation 4,479,320 1,042,300
Commodity Contracts [Member] | Payable on Open Futures Contracts, Unrealized Depreciation on Swap and/or Forward Agreements [Member] | ProShares UltraShort DJ-UBS Commodity [Member]
   
Derivative Instruments, Gain (Loss) [Line Items]    
Derivative liability not designated as hedging instrument, Unrealized Depreciation 114,128  
Commodity Contracts [Member] | Payable on Open Futures Contracts, Unrealized Depreciation on Swap and/or Forward Agreements [Member] | ProShares UltraShort DJ-UBS Crude Oil [Member]
   
Derivative Instruments, Gain (Loss) [Line Items]    
Derivative liability not designated as hedging instrument, Unrealized Depreciation 7,028,464 3,565,673
Commodity Contracts [Member] | Payable on Open Futures Contracts, Unrealized Depreciation on Swap and/or Forward Agreements [Member] | ProShares Ultra DJ-UBS Natural Gas [Member]
   
Derivative Instruments, Gain (Loss) [Line Items]    
Derivative liability not designated as hedging instrument, Unrealized Depreciation   3,656,539
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 12,026,932  
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 58,143,691 2,227,857
Commodity Contracts [Member] | Payable on Open Futures Contracts, Unrealized Depreciation on Swap and/or Forward Agreements [Member] | ProShares Short Euro [Member]
   
Derivative Instruments, Gain (Loss) [Line Items]    
Derivative liability not designated as hedging instrument, Unrealized Depreciation 1,851,411  
Commodity Contracts [Member] | Payable on Open Futures Contracts, Unrealized Depreciation on Swap and/or Forward Agreements [Member] | ProShares Ultra DJ-UBS Commodity [Member]
   
Derivative Instruments, Gain (Loss) [Line Items]    
Derivative liability not designated as hedging instrument, Unrealized Depreciation   27,665
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
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   33,231
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 1,221,879  
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 3,724,310 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 1,275,150 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 35 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 42,233 163,361
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 192,985 917,605
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 47,900 151,351
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 6,121,534 31,317,568
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 21,019 120,908
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 1,004 4,052
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 8,083,199 8,116,955
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 5,026,965 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 2,007,210 4,896,689
VIX Futures Contracts [Member] | Payable on Open Futures Contracts and Unrealized Depreciation on Swap Agreements [Member] | ProShares Short VIX Short-Term Futures ETF [Member]
   
Derivative Instruments, Gain (Loss) [Line Items]    
Derivative liability not designated as hedging instrument, Unrealized Depreciation 29,701,827  
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   $ 24,009,911