v3.10.0.1

Creation and Redemption of Creation Units - Additional Information (Detail) | 6 Months Ended
--- | ---
Jun. 30, 2018 $ / EquityUnit shares
Creation And Redemption Of Creation Units [Line Items] |
Creation Unit, block Shares of a Fund | 50,000
Fixed transaction fee per Creation Unit, maximum | $ / EquityUnit | 250
Variable transaction fee, percent of the value of the Creation Unit, maximum | 0.10%
Volatility Index Fund [Member] |
Creation And Redemption Of Creation Units [Line Items] |
Creation Unit, block Shares of a Fund | 25,000
Variable transaction fee, percent of the value of the Creation Unit, maximum | 0.05%

X
- Definition Creation and redemption of creation units. + References No definition available. + Details
Name: | ck0001415311_CreationAndRedemptionOfCreationUnitsLineItems
Namespace Prefix: | ck0001415311_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Definition Creation unit, block shares of a fund. + References No definition available. + Details
Name: | ck0001415311_CreationUnitBlockSharesOfFund
Namespace Prefix: | ck0001415311_
Data Type: | xbrli:sharesItemType
Balance Type: | na
Period Type: | duration

X
- Definition Fixed transaction fee per creation unit, maximum. + References No definition available. + Details
Name: | ck0001415311_FixedTransactionFeePerCreationUnitMaximum
Namespace Prefix: | ck0001415311_
Data Type: | us-types:perUnitItemType
Balance Type: | na
Period Type: | duration

X
- Definition Variable transaction fee, percent of the value of the creation unit, maximum. + References No definition available. + Details
Name: | ck0001415311_VariableTransactionFeePercentOfValueOfCreationUnitMaximum
Namespace Prefix: | ck0001415311_
Data Type: | num:percentItemType
Balance Type: | na
Period Type: | duration

X
- Details
Name: | us-gaap_InvestmentTypeAxis=ck0001415311_VolatilityIndexFundMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |