v2.4.1.9

Risk - Additional Information (Detail) | 3 Months Ended
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Mar. 31, 2015
Unusual Risk or Uncertainty [Line Items] |
Percentage of calculation on simple inverse correlation | 200.00%ck0001415311_PercentageOfCalculationOnSimpleInverseCorrelation
Forward Agreements [Member] |
Unusual Risk or Uncertainty [Line Items] |
Exposure to swap agreements or forward contracts | 100.00%ck0001415311_PercentageOfCreditExposure / us-gaap_InvestmentTypeAxis = us-gaap_ForwardContractsMember
UltraShort Fund [Member] |
Unusual Risk or Uncertainty [Line Items] |
Leverage risk benchmark | 50% at any point in the day
Managed Futures Fund [Member] | ProShares Morningstar Alternatives Solution ETF [Member] |
Unusual Risk or Uncertainty [Line Items] |
Equity ownership percentage | 65.00%us-gaap_EquityMethodInvestmentOwnershipPercentage / us-gaap_InvestmentTypeAxis = ck0001415311_ManagedFuturesFundMember / us-gaap_StatementBusinessSegmentsAxis = ck0001415311_ProsharesMorningstarAlternativesSolutionEtfMember

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- Definition Percentage of calculation on simple inverse correlation. + References No definition available. + Details
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Namespace Prefix: | ck0001415311_
Data Type: | num:percentItemType
Balance Type: | na
Period Type: | duration

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- Definition Percentage of credit exposure. + References No definition available. + Details
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Namespace Prefix: | ck0001415311_
Data Type: | num:percentItemType
Balance Type: | na
Period Type: | duration

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- Definition Risk related to changes in benchmark interest rate. + References No definition available. + Details
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Namespace Prefix: | ck0001415311_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

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- Definition The percentage of ownership of common stock or equity participation in the investee accounted for under the equity method of accounting. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 323 -SubTopic 10 -Section 50 -Paragraph 3 -Subparagraph (a)(1) -URI http://asc.fasb.org/extlink&oid=6382943&loc=d3e33918-111571 + Details
Name: | us-gaap_EquityMethodInvestmentOwnershipPercentage
Namespace Prefix: | us-gaap_
Data Type: | num:percentItemType
Balance Type: | na
Period Type: | instant

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- Details
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Namespace Prefix: | us-gaap_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

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- Details
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Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

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- Details
Name: | us-gaap_InvestmentTypeAxis=ck0001415311_UltrashortFundMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

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- Details
Name: | us-gaap_InvestmentTypeAxis=us-gaap_ForwardContractsMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |