v2.4.1.9

Risk - Additional Information (Detail)	3 Months Ended
	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

X

- Definition

Percentage of calculation on simple inverse correlation.

+ References

No definition available.

+ Details

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Data Type:	num:percentItemType
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X

- Definition

Percentage of credit exposure.

+ References

No definition available.

+ Details

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Period Type:	duration

X

- 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
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Period Type:	duration

X

- 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

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Period Type:	instant

X

- Details

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- Details

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Period Type:

X

- Details

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

X

- Details

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Period Type: