v2.4.1.9
Investments - Fair Value of Derivative Instruments (Detail) (USD $)
Mar. 31, 2015
Dec. 31, 2014
Derivative Instruments, Gain (Loss) [Line Items]    
Derivative asset not designated as hedging instrument, Unrealized Appreciation $ 112,237,936ck0001415311_DerivativeAssetNotDesignatedAsHedgingInstrumentUnrealizedAppreciation [1] $ 117,369,486ck0001415311_DerivativeAssetNotDesignatedAsHedgingInstrumentUnrealizedAppreciation [2]
Derivative liability not designated as hedging instrument, Unrealized Depreciation 221,525,982ck0001415311_DerivativeLiabilityNotDesignatedAsHedgingInstrumentUnrealizedDepreciation [1] 193,984,012ck0001415311_DerivativeLiabilityNotDesignatedAsHedgingInstrumentUnrealizedDepreciation [2]
Managed Futures Contracts [Member] | Payable on Open Futures Contracts [Member] | ProShares Managed Futures Strategy [Member]    
Derivative Instruments, Gain (Loss) [Line Items]    
Derivative liability not designated as hedging instrument, Unrealized Depreciation 107,342ck0001415311_DerivativeLiabilityNotDesignatedAsHedgingInstrumentUnrealizedDepreciation
/ us-gaap_BalanceSheetLocationAxis
= ck0001415311_PayableOnOpenFuturesContractsMember
/ us-gaap_DerivativeInstrumentRiskAxis
= ck0001415311_FuturesContractsMember
/ us-gaap_StatementBusinessSegmentsAxis
= ck0001415311_ProsharesManagedFuturesStrategyMember		 [1] 18,504ck0001415311_DerivativeLiabilityNotDesignatedAsHedgingInstrumentUnrealizedDepreciation
/ us-gaap_BalanceSheetLocationAxis
= ck0001415311_PayableOnOpenFuturesContractsMember
/ us-gaap_DerivativeInstrumentRiskAxis
= ck0001415311_FuturesContractsMember
/ us-gaap_StatementBusinessSegmentsAxis
= ck0001415311_ProsharesManagedFuturesStrategyMember		 [2]
Managed Futures Contracts [Member] | Receivables on Open Futures Contracts [Member] | ProShares Managed Futures Strategy [Member]    
Derivative Instruments, Gain (Loss) [Line Items]    
Derivative asset not designated as hedging instrument, Unrealized Appreciation 190,575ck0001415311_DerivativeAssetNotDesignatedAsHedgingInstrumentUnrealizedAppreciation
/ us-gaap_BalanceSheetLocationAxis
= ck0001415311_ReceivablesOnOpenFuturesContractsMember
/ us-gaap_DerivativeInstrumentRiskAxis
= ck0001415311_FuturesContractsMember
/ us-gaap_StatementBusinessSegmentsAxis
= ck0001415311_ProsharesManagedFuturesStrategyMember		 [1] 122,831ck0001415311_DerivativeAssetNotDesignatedAsHedgingInstrumentUnrealizedAppreciation
/ us-gaap_BalanceSheetLocationAxis
= ck0001415311_ReceivablesOnOpenFuturesContractsMember
/ us-gaap_DerivativeInstrumentRiskAxis
= ck0001415311_FuturesContractsMember
/ us-gaap_StatementBusinessSegmentsAxis
= ck0001415311_ProsharesManagedFuturesStrategyMember		 [2]
VIX Futures Contracts [Member] | Payable on Open Futures Contracts [Member] | ProShares VIX Short-Term Futures ETF [Member]    
Derivative Instruments, Gain (Loss) [Line Items]    
Derivative liability not designated as hedging instrument, Unrealized Depreciation 5,816,262ck0001415311_DerivativeLiabilityNotDesignatedAsHedgingInstrumentUnrealizedDepreciation
/ us-gaap_BalanceSheetLocationAxis
= ck0001415311_PayableOnOpenFuturesContractsMember
/ us-gaap_DerivativeInstrumentRiskAxis
= us-gaap_FutureMember
/ us-gaap_StatementBusinessSegmentsAxis
= ck0001415311_ProsharesVixShortTermFuturesEtfMember		 [1]  
VIX Futures Contracts [Member] | Payable on Open Futures Contracts [Member] | ProShares VIX Mid-Term Futures ETF [Member]    
Derivative Instruments, Gain (Loss) [Line Items]    
Derivative liability not designated as hedging instrument, Unrealized Depreciation 616,590ck0001415311_DerivativeLiabilityNotDesignatedAsHedgingInstrumentUnrealizedDepreciation
/ us-gaap_BalanceSheetLocationAxis
= ck0001415311_PayableOnOpenFuturesContractsMember
/ us-gaap_DerivativeInstrumentRiskAxis
= us-gaap_FutureMember
/ us-gaap_StatementBusinessSegmentsAxis
= ck0001415311_ProsharesVixMidTermFuturesEtfMember		 [1] 222,845ck0001415311_DerivativeLiabilityNotDesignatedAsHedgingInstrumentUnrealizedDepreciation
/ us-gaap_BalanceSheetLocationAxis
= ck0001415311_PayableOnOpenFuturesContractsMember
/ us-gaap_DerivativeInstrumentRiskAxis
= us-gaap_FutureMember
/ us-gaap_StatementBusinessSegmentsAxis
= ck0001415311_ProsharesVixMidTermFuturesEtfMember		 [2]
VIX Futures Contracts [Member] | Payable on Open Futures Contracts [Member] | ProShares Short VIX Short-Term Futures ETF [Member]    
Derivative Instruments, Gain (Loss) [Line Items]    
Derivative liability not designated as hedging instrument, Unrealized Depreciation 1,599,750ck0001415311_DerivativeLiabilityNotDesignatedAsHedgingInstrumentUnrealizedDepreciation
/ us-gaap_BalanceSheetLocationAxis
= ck0001415311_PayableOnOpenFuturesContractsMember
/ us-gaap_DerivativeInstrumentRiskAxis
= us-gaap_FutureMember
/ us-gaap_StatementBusinessSegmentsAxis
= ck0001415311_ProsharesShortVixShortTermFuturesEtfMember		 16,352,149ck0001415311_DerivativeLiabilityNotDesignatedAsHedgingInstrumentUnrealizedDepreciation
/ us-gaap_BalanceSheetLocationAxis
= ck0001415311_PayableOnOpenFuturesContractsMember
/ us-gaap_DerivativeInstrumentRiskAxis
= us-gaap_FutureMember
/ us-gaap_StatementBusinessSegmentsAxis
= ck0001415311_ProsharesShortVixShortTermFuturesEtfMember		 [2]
VIX Futures Contracts [Member] | Payable on Open Futures Contracts [Member] | ProShares Ultra VIX Short-Term Futures ETF [Member]    
Derivative Instruments, Gain (Loss) [Line Items]    
Derivative liability not designated as hedging instrument, Unrealized Depreciation 55,127,903ck0001415311_DerivativeLiabilityNotDesignatedAsHedgingInstrumentUnrealizedDepreciation
/ us-gaap_BalanceSheetLocationAxis
= ck0001415311_PayableOnOpenFuturesContractsMember
/ us-gaap_DerivativeInstrumentRiskAxis
= us-gaap_FutureMember
/ us-gaap_StatementBusinessSegmentsAxis
= ck0001415311_ProsharesUltraVixShortTermFuturesEtfMember		  
VIX Futures Contracts [Member] | Receivables on Open Futures Contracts [Member] | ProShares VIX Short-Term Futures ETF [Member]    
Derivative Instruments, Gain (Loss) [Line Items]    
Derivative asset not designated as hedging instrument, Unrealized Appreciation 710,151ck0001415311_DerivativeAssetNotDesignatedAsHedgingInstrumentUnrealizedAppreciation
/ us-gaap_BalanceSheetLocationAxis
= ck0001415311_ReceivablesOnOpenFuturesContractsMember
/ us-gaap_DerivativeInstrumentRiskAxis
= us-gaap_FutureMember
/ us-gaap_StatementBusinessSegmentsAxis
= ck0001415311_ProsharesVixShortTermFuturesEtfMember		 [1] 6,264,620ck0001415311_DerivativeAssetNotDesignatedAsHedgingInstrumentUnrealizedAppreciation
/ us-gaap_BalanceSheetLocationAxis
= ck0001415311_ReceivablesOnOpenFuturesContractsMember
/ us-gaap_DerivativeInstrumentRiskAxis
= us-gaap_FutureMember
/ us-gaap_StatementBusinessSegmentsAxis
= ck0001415311_ProsharesVixShortTermFuturesEtfMember		 [2]
VIX Futures Contracts [Member] | Receivables on Open Futures Contracts [Member] | ProShares VIX Mid-Term Futures ETF [Member]    
Derivative Instruments, Gain (Loss) [Line Items]    
Derivative asset not designated as hedging instrument, Unrealized Appreciation 116,200ck0001415311_DerivativeAssetNotDesignatedAsHedgingInstrumentUnrealizedAppreciation
/ us-gaap_BalanceSheetLocationAxis
= ck0001415311_ReceivablesOnOpenFuturesContractsMember
/ us-gaap_DerivativeInstrumentRiskAxis
= us-gaap_FutureMember
/ us-gaap_StatementBusinessSegmentsAxis
= ck0001415311_ProsharesVixMidTermFuturesEtfMember		 [1] 483,510ck0001415311_DerivativeAssetNotDesignatedAsHedgingInstrumentUnrealizedAppreciation
/ us-gaap_BalanceSheetLocationAxis
= ck0001415311_ReceivablesOnOpenFuturesContractsMember
/ us-gaap_DerivativeInstrumentRiskAxis
= us-gaap_FutureMember
/ us-gaap_StatementBusinessSegmentsAxis
= ck0001415311_ProsharesVixMidTermFuturesEtfMember		 [2]
VIX Futures Contracts [Member] | Receivables on Open Futures Contracts [Member] | ProShares Short VIX Short-Term Futures ETF [Member]    
Derivative Instruments, Gain (Loss) [Line Items]    
Derivative asset not designated as hedging instrument, Unrealized Appreciation 8,591,734ck0001415311_DerivativeAssetNotDesignatedAsHedgingInstrumentUnrealizedAppreciation
/ us-gaap_BalanceSheetLocationAxis
= ck0001415311_ReceivablesOnOpenFuturesContractsMember
/ us-gaap_DerivativeInstrumentRiskAxis
= us-gaap_FutureMember
/ us-gaap_StatementBusinessSegmentsAxis
= ck0001415311_ProsharesShortVixShortTermFuturesEtfMember		 [1]  
VIX Futures Contracts [Member] | Receivables on Open Futures Contracts [Member] | ProShares Ultra VIX Short-Term Futures ETF [Member]    
Derivative Instruments, Gain (Loss) [Line Items]    
Derivative asset not designated as hedging instrument, Unrealized Appreciation 6,202,210ck0001415311_DerivativeAssetNotDesignatedAsHedgingInstrumentUnrealizedAppreciation
/ us-gaap_BalanceSheetLocationAxis
= ck0001415311_ReceivablesOnOpenFuturesContractsMember
/ us-gaap_DerivativeInstrumentRiskAxis
= us-gaap_FutureMember
/ us-gaap_StatementBusinessSegmentsAxis
= ck0001415311_ProsharesUltraVixShortTermFuturesEtfMember		 39,585,253ck0001415311_DerivativeAssetNotDesignatedAsHedgingInstrumentUnrealizedAppreciation
/ us-gaap_BalanceSheetLocationAxis
= ck0001415311_ReceivablesOnOpenFuturesContractsMember
/ us-gaap_DerivativeInstrumentRiskAxis
= us-gaap_FutureMember
/ us-gaap_StatementBusinessSegmentsAxis
= ck0001415311_ProsharesUltraVixShortTermFuturesEtfMember		 [2]
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 3,736,183ck0001415311_DerivativeLiabilityNotDesignatedAsHedgingInstrumentUnrealizedDepreciation
/ us-gaap_BalanceSheetLocationAxis
= ck0001415311_PayableOnOpenFuturesContractsUnrealizedDepreciationOnSwapAndOrForwardAgreementsMember
/ us-gaap_DerivativeInstrumentRiskAxis
= us-gaap_CommodityContractMember
/ us-gaap_StatementBusinessSegmentsAxis
= ck0001415311_ProsharesUltrashortSilverMember		 204,570ck0001415311_DerivativeLiabilityNotDesignatedAsHedgingInstrumentUnrealizedDepreciation
/ us-gaap_BalanceSheetLocationAxis
= ck0001415311_PayableOnOpenFuturesContractsUnrealizedDepreciationOnSwapAndOrForwardAgreementsMember
/ us-gaap_DerivativeInstrumentRiskAxis
= us-gaap_CommodityContractMember
/ us-gaap_StatementBusinessSegmentsAxis
= ck0001415311_ProsharesUltrashortSilverMember
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 3,320ck0001415311_DerivativeLiabilityNotDesignatedAsHedgingInstrumentUnrealizedDepreciation
/ us-gaap_BalanceSheetLocationAxis
= ck0001415311_PayableOnOpenFuturesContractsUnrealizedDepreciationOnSwapAndOrForwardAgreementsMember
/ us-gaap_DerivativeInstrumentRiskAxis
= us-gaap_CommodityContractMember
/ us-gaap_StatementBusinessSegmentsAxis
= ck0001415311_ProsharesUltraSilverMember		 [1] 12,396,680ck0001415311_DerivativeLiabilityNotDesignatedAsHedgingInstrumentUnrealizedDepreciation
/ us-gaap_BalanceSheetLocationAxis
= ck0001415311_PayableOnOpenFuturesContractsUnrealizedDepreciationOnSwapAndOrForwardAgreementsMember
/ us-gaap_DerivativeInstrumentRiskAxis
= us-gaap_CommodityContractMember
/ us-gaap_StatementBusinessSegmentsAxis
= ck0001415311_ProsharesUltraSilverMember		 [2]
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 1,588,121ck0001415311_DerivativeLiabilityNotDesignatedAsHedgingInstrumentUnrealizedDepreciation
/ us-gaap_BalanceSheetLocationAxis
= ck0001415311_PayableOnOpenFuturesContractsUnrealizedDepreciationOnSwapAndOrForwardAgreementsMember
/ us-gaap_DerivativeInstrumentRiskAxis
= us-gaap_CommodityContractMember
/ us-gaap_StatementBusinessSegmentsAxis
= ck0001415311_ProsharesUltrashortGoldMember		 [1] 2,287,298ck0001415311_DerivativeLiabilityNotDesignatedAsHedgingInstrumentUnrealizedDepreciation
/ us-gaap_BalanceSheetLocationAxis
= ck0001415311_PayableOnOpenFuturesContractsUnrealizedDepreciationOnSwapAndOrForwardAgreementsMember
/ us-gaap_DerivativeInstrumentRiskAxis
= us-gaap_CommodityContractMember
/ us-gaap_StatementBusinessSegmentsAxis
= ck0001415311_ProsharesUltrashortGoldMember		 [2]
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 129,433ck0001415311_DerivativeLiabilityNotDesignatedAsHedgingInstrumentUnrealizedDepreciation
/ us-gaap_BalanceSheetLocationAxis
= ck0001415311_PayableOnOpenFuturesContractsUnrealizedDepreciationOnSwapAndOrForwardAgreementsMember
/ us-gaap_DerivativeInstrumentRiskAxis
= us-gaap_CommodityContractMember
/ us-gaap_StatementBusinessSegmentsAxis
= ck0001415311_ProsharesUltraBloombergCommodityMember		 331,338ck0001415311_DerivativeLiabilityNotDesignatedAsHedgingInstrumentUnrealizedDepreciation
/ us-gaap_BalanceSheetLocationAxis
= ck0001415311_PayableOnOpenFuturesContractsUnrealizedDepreciationOnSwapAndOrForwardAgreementsMember
/ us-gaap_DerivativeInstrumentRiskAxis
= us-gaap_CommodityContractMember
/ us-gaap_StatementBusinessSegmentsAxis
= ck0001415311_ProsharesUltraBloombergCommodityMember
Commodity Contracts [Member] | Payable on Open Futures Contracts, Unrealized Depreciation on Swap and/or Forward Agreements [Member] | ProShares Ultra Bloomberg Crude Oil [Member]    
Derivative Instruments, Gain (Loss) [Line Items]    
Derivative liability not designated as hedging instrument, Unrealized Depreciation 142,337,660ck0001415311_DerivativeLiabilityNotDesignatedAsHedgingInstrumentUnrealizedDepreciation
/ us-gaap_BalanceSheetLocationAxis
= ck0001415311_PayableOnOpenFuturesContractsUnrealizedDepreciationOnSwapAndOrForwardAgreementsMember
/ us-gaap_DerivativeInstrumentRiskAxis
= us-gaap_CommodityContractMember
/ us-gaap_StatementBusinessSegmentsAxis
= ck0001415311_ProsharesUltraBloombergCrudeOilMember		 [1] 122,655,884ck0001415311_DerivativeLiabilityNotDesignatedAsHedgingInstrumentUnrealizedDepreciation
/ us-gaap_BalanceSheetLocationAxis
= ck0001415311_PayableOnOpenFuturesContractsUnrealizedDepreciationOnSwapAndOrForwardAgreementsMember
/ us-gaap_DerivativeInstrumentRiskAxis
= us-gaap_CommodityContractMember
/ us-gaap_StatementBusinessSegmentsAxis
= ck0001415311_ProsharesUltraBloombergCrudeOilMember		 [2]
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 7,437,631ck0001415311_DerivativeLiabilityNotDesignatedAsHedgingInstrumentUnrealizedDepreciation
/ us-gaap_BalanceSheetLocationAxis
= ck0001415311_PayableOnOpenFuturesContractsUnrealizedDepreciationOnSwapAndOrForwardAgreementsMember
/ us-gaap_DerivativeInstrumentRiskAxis
= us-gaap_CommodityContractMember
/ us-gaap_StatementBusinessSegmentsAxis
= ck0001415311_ProsharesUltraBloombergNaturalGasMember		 [1] 34,889,283ck0001415311_DerivativeLiabilityNotDesignatedAsHedgingInstrumentUnrealizedDepreciation
/ us-gaap_BalanceSheetLocationAxis
= ck0001415311_PayableOnOpenFuturesContractsUnrealizedDepreciationOnSwapAndOrForwardAgreementsMember
/ us-gaap_DerivativeInstrumentRiskAxis
= us-gaap_CommodityContractMember
/ us-gaap_StatementBusinessSegmentsAxis
= ck0001415311_ProsharesUltraBloombergNaturalGasMember		 [2]
Commodity Contracts [Member] | Receivables on Open Futures Contracts, Unrealized Appreciation on Swap and/ or Forwards Agreements [Member] | ProShares UltraShort Bloomberg Commodity [Member]    
Derivative Instruments, Gain (Loss) [Line Items]    
Derivative asset not designated as hedging instrument, Unrealized Appreciation 276,625ck0001415311_DerivativeAssetNotDesignatedAsHedgingInstrumentUnrealizedAppreciation
/ us-gaap_BalanceSheetLocationAxis
= ck0001415311_ReceivablesOnOpenFuturesContractsUnrealizedAppreciationOnSwapAndOrForwardContractsMember
/ us-gaap_DerivativeInstrumentRiskAxis
= us-gaap_CommodityContractMember
/ us-gaap_StatementBusinessSegmentsAxis
= ck0001415311_ProsharesUltrashortBloombergCommodityMember		 567,259ck0001415311_DerivativeAssetNotDesignatedAsHedgingInstrumentUnrealizedAppreciation
/ us-gaap_BalanceSheetLocationAxis
= ck0001415311_ReceivablesOnOpenFuturesContractsUnrealizedAppreciationOnSwapAndOrForwardContractsMember
/ us-gaap_DerivativeInstrumentRiskAxis
= us-gaap_CommodityContractMember
/ us-gaap_StatementBusinessSegmentsAxis
= ck0001415311_ProsharesUltrashortBloombergCommodityMember
Commodity Contracts [Member] | Receivables on Open Futures Contracts, Unrealized Appreciation on Swap and/ or Forwards Agreements [Member] | ProShares UltraShort Bloomberg Crude Oil [Member]    
Derivative Instruments, Gain (Loss) [Line Items]    
Derivative asset not designated as hedging instrument, Unrealized Appreciation 44,263,734ck0001415311_DerivativeAssetNotDesignatedAsHedgingInstrumentUnrealizedAppreciation
/ us-gaap_BalanceSheetLocationAxis
= ck0001415311_ReceivablesOnOpenFuturesContractsUnrealizedAppreciationOnSwapAndOrForwardContractsMember
/ us-gaap_DerivativeInstrumentRiskAxis
= us-gaap_CommodityContractMember
/ us-gaap_StatementBusinessSegmentsAxis
= ck0001415311_ProsharesUltrashortBloombergCrudeOilMember		 [1] 42,824,680ck0001415311_DerivativeAssetNotDesignatedAsHedgingInstrumentUnrealizedAppreciation
/ us-gaap_BalanceSheetLocationAxis
= ck0001415311_ReceivablesOnOpenFuturesContractsUnrealizedAppreciationOnSwapAndOrForwardContractsMember
/ us-gaap_DerivativeInstrumentRiskAxis
= us-gaap_CommodityContractMember
/ us-gaap_StatementBusinessSegmentsAxis
= ck0001415311_ProsharesUltrashortBloombergCrudeOilMember		 [2]
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 859,740ck0001415311_DerivativeAssetNotDesignatedAsHedgingInstrumentUnrealizedAppreciation
/ us-gaap_BalanceSheetLocationAxis
= ck0001415311_ReceivablesOnOpenFuturesContractsUnrealizedAppreciationOnSwapAndOrForwardContractsMember
/ us-gaap_DerivativeInstrumentRiskAxis
= us-gaap_CommodityContractMember
/ us-gaap_StatementBusinessSegmentsAxis
= ck0001415311_ProsharesUltrashortBloombergNaturalGasMember		 [1] 3,941,465ck0001415311_DerivativeAssetNotDesignatedAsHedgingInstrumentUnrealizedAppreciation
/ us-gaap_BalanceSheetLocationAxis
= ck0001415311_ReceivablesOnOpenFuturesContractsUnrealizedAppreciationOnSwapAndOrForwardContractsMember
/ us-gaap_DerivativeInstrumentRiskAxis
= us-gaap_CommodityContractMember
/ us-gaap_StatementBusinessSegmentsAxis
= ck0001415311_ProsharesUltrashortBloombergNaturalGasMember		 [2]
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 3,095ck0001415311_DerivativeAssetNotDesignatedAsHedgingInstrumentUnrealizedAppreciation
/ us-gaap_BalanceSheetLocationAxis
= ck0001415311_ReceivablesOnOpenFuturesContractsUnrealizedAppreciationOnSwapAndOrForwardContractsMember
/ us-gaap_DerivativeInstrumentRiskAxis
= us-gaap_CommodityContractMember
/ us-gaap_StatementBusinessSegmentsAxis
= ck0001415311_ProsharesUltrashortSilverMember		 [1] 801,083ck0001415311_DerivativeAssetNotDesignatedAsHedgingInstrumentUnrealizedAppreciation
/ us-gaap_BalanceSheetLocationAxis
= ck0001415311_ReceivablesOnOpenFuturesContractsUnrealizedAppreciationOnSwapAndOrForwardContractsMember
/ us-gaap_DerivativeInstrumentRiskAxis
= us-gaap_CommodityContractMember
/ us-gaap_StatementBusinessSegmentsAxis
= ck0001415311_ProsharesUltrashortSilverMember		 [2]
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 1,666,988ck0001415311_DerivativeAssetNotDesignatedAsHedgingInstrumentUnrealizedAppreciation
/ us-gaap_BalanceSheetLocationAxis
= ck0001415311_ReceivablesOnOpenFuturesContractsUnrealizedAppreciationOnSwapAndOrForwardContractsMember
/ us-gaap_DerivativeInstrumentRiskAxis
= us-gaap_CommodityContractMember
/ us-gaap_StatementBusinessSegmentsAxis
= ck0001415311_ProsharesUltraGoldMember		 [1] 2,055,734ck0001415311_DerivativeAssetNotDesignatedAsHedgingInstrumentUnrealizedAppreciation
/ us-gaap_BalanceSheetLocationAxis
= ck0001415311_ReceivablesOnOpenFuturesContractsUnrealizedAppreciationOnSwapAndOrForwardContractsMember
/ us-gaap_DerivativeInstrumentRiskAxis
= us-gaap_CommodityContractMember
/ us-gaap_StatementBusinessSegmentsAxis
= ck0001415311_ProsharesUltraGoldMember		 [2]
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 22,620,868ck0001415311_DerivativeAssetNotDesignatedAsHedgingInstrumentUnrealizedAppreciation
/ us-gaap_BalanceSheetLocationAxis
= ck0001415311_ReceivablesOnOpenFuturesContractsUnrealizedAppreciationOnSwapAndOrForwardContractsMember
/ us-gaap_DerivativeInstrumentRiskAxis
= us-gaap_CommodityContractMember
/ us-gaap_StatementBusinessSegmentsAxis
= ck0001415311_ProsharesUltraSilverMember		  
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 2,088,667ck0001415311_DerivativeLiabilityNotDesignatedAsHedgingInstrumentUnrealizedDepreciation
/ us-gaap_BalanceSheetLocationAxis
= ck0001415311_UnrealizedDepreciationOnForeignCurrencyForwardContractsMember
/ us-gaap_DerivativeInstrumentRiskAxis
= us-gaap_ForeignExchangeContractMember
/ us-gaap_StatementBusinessSegmentsAxis
= ck0001415311_ProsharesUltrashortEuroMember		 2,256,771ck0001415311_DerivativeLiabilityNotDesignatedAsHedgingInstrumentUnrealizedDepreciation
/ us-gaap_BalanceSheetLocationAxis
= ck0001415311_UnrealizedDepreciationOnForeignCurrencyForwardContractsMember
/ us-gaap_DerivativeInstrumentRiskAxis
= us-gaap_ForeignExchangeContractMember
/ us-gaap_StatementBusinessSegmentsAxis
= ck0001415311_ProsharesUltrashortEuroMember
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 57,733ck0001415311_DerivativeLiabilityNotDesignatedAsHedgingInstrumentUnrealizedDepreciation
/ us-gaap_BalanceSheetLocationAxis
= ck0001415311_UnrealizedDepreciationOnForeignCurrencyForwardContractsMember
/ us-gaap_DerivativeInstrumentRiskAxis
= us-gaap_ForeignExchangeContractMember
/ us-gaap_StatementBusinessSegmentsAxis
= ck0001415311_ProsharesUltrashortYenMember		 2,149,924ck0001415311_DerivativeLiabilityNotDesignatedAsHedgingInstrumentUnrealizedDepreciation
/ us-gaap_BalanceSheetLocationAxis
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= us-gaap_ForeignExchangeContractMember
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= ck0001415311_ProsharesUltrashortYenMember
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 780,795ck0001415311_DerivativeLiabilityNotDesignatedAsHedgingInstrumentUnrealizedDepreciation
/ us-gaap_BalanceSheetLocationAxis
= ck0001415311_UnrealizedDepreciationOnForeignCurrencyForwardContractsMember
/ us-gaap_DerivativeInstrumentRiskAxis
= us-gaap_ForeignExchangeContractMember
/ us-gaap_StatementBusinessSegmentsAxis
= ck0001415311_ProsharesUltraEuroMember		 106,292ck0001415311_DerivativeLiabilityNotDesignatedAsHedgingInstrumentUnrealizedDepreciation
/ us-gaap_BalanceSheetLocationAxis
= ck0001415311_UnrealizedDepreciationOnForeignCurrencyForwardContractsMember
/ us-gaap_DerivativeInstrumentRiskAxis
= us-gaap_ForeignExchangeContractMember
/ us-gaap_StatementBusinessSegmentsAxis
= ck0001415311_ProsharesUltraEuroMember
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 57,414ck0001415311_DerivativeLiabilityNotDesignatedAsHedgingInstrumentUnrealizedDepreciation
/ us-gaap_BalanceSheetLocationAxis
= ck0001415311_UnrealizedDepreciationOnForeignCurrencyForwardContractsMember
/ us-gaap_DerivativeInstrumentRiskAxis
= us-gaap_ForeignExchangeContractMember
/ us-gaap_StatementBusinessSegmentsAxis
= ck0001415311_ProsharesUltraAustralianDollarMember		 [1] 96,825ck0001415311_DerivativeLiabilityNotDesignatedAsHedgingInstrumentUnrealizedDepreciation
/ us-gaap_BalanceSheetLocationAxis
= ck0001415311_UnrealizedDepreciationOnForeignCurrencyForwardContractsMember
/ us-gaap_DerivativeInstrumentRiskAxis
= us-gaap_ForeignExchangeContractMember
/ us-gaap_StatementBusinessSegmentsAxis
= ck0001415311_ProsharesUltraAustralianDollarMember		 [2]
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 41,178ck0001415311_DerivativeLiabilityNotDesignatedAsHedgingInstrumentUnrealizedDepreciation
/ us-gaap_BalanceSheetLocationAxis
= ck0001415311_UnrealizedDepreciationOnForeignCurrencyForwardContractsMember
/ us-gaap_DerivativeInstrumentRiskAxis
= us-gaap_ForeignExchangeContractMember
/ us-gaap_StatementBusinessSegmentsAxis
= ck0001415311_ProsharesUltraYenMember		 15,649ck0001415311_DerivativeLiabilityNotDesignatedAsHedgingInstrumentUnrealizedDepreciation
/ us-gaap_BalanceSheetLocationAxis
= ck0001415311_UnrealizedDepreciationOnForeignCurrencyForwardContractsMember
/ us-gaap_DerivativeInstrumentRiskAxis
= us-gaap_ForeignExchangeContractMember
/ us-gaap_StatementBusinessSegmentsAxis
= ck0001415311_ProsharesUltraYenMember
Foreign Exchange Contracts [Member] | Unrealized Appreciation on Foreign Currency Forward Contracts and Receivables on Open Futures Contracts [Member] | ProShares Short Euro [Member]    
Derivative Instruments, Gain (Loss) [Line Items]    
Derivative asset not designated as hedging instrument, Unrealized Appreciation 109,769ck0001415311_DerivativeAssetNotDesignatedAsHedgingInstrumentUnrealizedAppreciation
/ us-gaap_BalanceSheetLocationAxis
= ck0001415311_UnrealizedAppreciationOnForeignCurrencyForwardContractsMember
/ us-gaap_DerivativeInstrumentRiskAxis
= us-gaap_ForeignExchangeContractMember
/ us-gaap_StatementBusinessSegmentsAxis
= ck0001415311_ProsharesShortEuroMember		 [1] 385,331ck0001415311_DerivativeAssetNotDesignatedAsHedgingInstrumentUnrealizedAppreciation
/ us-gaap_BalanceSheetLocationAxis
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/ us-gaap_DerivativeInstrumentRiskAxis
= us-gaap_ForeignExchangeContractMember
/ us-gaap_StatementBusinessSegmentsAxis
= ck0001415311_ProsharesShortEuroMember		 [2]
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 419,850ck0001415311_DerivativeAssetNotDesignatedAsHedgingInstrumentUnrealizedAppreciation
/ us-gaap_BalanceSheetLocationAxis
= ck0001415311_UnrealizedAppreciationOnForeignCurrencyForwardContractsMember
/ us-gaap_DerivativeInstrumentRiskAxis
= us-gaap_ForeignExchangeContractMember
/ us-gaap_StatementBusinessSegmentsAxis
= ck0001415311_ProsharesUltrashortAustralianDollarMember		 [1] 743,481ck0001415311_DerivativeAssetNotDesignatedAsHedgingInstrumentUnrealizedAppreciation
/ us-gaap_BalanceSheetLocationAxis
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/ us-gaap_DerivativeInstrumentRiskAxis
= us-gaap_ForeignExchangeContractMember
/ us-gaap_StatementBusinessSegmentsAxis
= ck0001415311_ProsharesUltrashortAustralianDollarMember		 [2]
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 25,478,862ck0001415311_DerivativeAssetNotDesignatedAsHedgingInstrumentUnrealizedAppreciation
/ us-gaap_BalanceSheetLocationAxis
= ck0001415311_UnrealizedAppreciationOnForeignCurrencyForwardContractsMember
/ us-gaap_DerivativeInstrumentRiskAxis
= us-gaap_ForeignExchangeContractMember
/ us-gaap_StatementBusinessSegmentsAxis
= ck0001415311_ProsharesUltrashortEuroMember		 19,019,765ck0001415311_DerivativeAssetNotDesignatedAsHedgingInstrumentUnrealizedAppreciation
/ us-gaap_BalanceSheetLocationAxis
= ck0001415311_UnrealizedAppreciationOnForeignCurrencyForwardContractsMember
/ us-gaap_DerivativeInstrumentRiskAxis
= us-gaap_ForeignExchangeContractMember
/ us-gaap_StatementBusinessSegmentsAxis
= ck0001415311_ProsharesUltrashortEuroMember
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 725,490ck0001415311_DerivativeAssetNotDesignatedAsHedgingInstrumentUnrealizedAppreciation
/ us-gaap_BalanceSheetLocationAxis
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/ us-gaap_DerivativeInstrumentRiskAxis
= us-gaap_ForeignExchangeContractMember
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= ck0001415311_ProsharesUltrashortYenMember		 571,149ck0001415311_DerivativeAssetNotDesignatedAsHedgingInstrumentUnrealizedAppreciation
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/ us-gaap_DerivativeInstrumentRiskAxis
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/ us-gaap_StatementBusinessSegmentsAxis
= ck0001415311_ProsharesUltrashortYenMember
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 2,045ck0001415311_DerivativeAssetNotDesignatedAsHedgingInstrumentUnrealizedAppreciation
/ us-gaap_BalanceSheetLocationAxis
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/ us-gaap_DerivativeInstrumentRiskAxis
= us-gaap_ForeignExchangeContractMember
/ us-gaap_StatementBusinessSegmentsAxis
= ck0001415311_ProsharesUltraEuroMember
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   $ 404ck0001415311_DerivativeAssetNotDesignatedAsHedgingInstrumentUnrealizedAppreciation
/ us-gaap_BalanceSheetLocationAxis
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[1] Includes cumulative appreciation/depreciation of futures contracts as reported in the Schedules of Investments. Only current day's variation margin is reported within the Statements of Financial Condition in receivable/payable on open futures contracts.
[2] Includes cumulative appreciation/depreciation of futures contracts as reported in the Schedules of Investments as presented in the Form 10-K for the year ended December 31, 2014. Only current day's variation margin is reported within the Statements of Financial Condition as presented in the Form 10-K for the year ended December 31, 2014 in receivable/payable on open futures contracts.