v3.21.1

Risk - Additional Information (Detail) | 3 Months Ended
--- | ---
Mar. 31, 2021
Unusual Risk or Uncertainty [Line Items] |
Inverse correlation, description | The return of a Geared Fund for a period longer than a single day is the result of its return for each day compounded over the period and usually will differ in amount and possibly even direction from one-half the inverse (-0.5x), the inverse (-1x), two times the inverse (-2x), one and one-half times (1.5x) the return or two times (2x) the return of the Geared Fund’s benchmark for the period.
Ultrashort Fund [Member] |
Unusual Risk or Uncertainty [Line Items] |
Leverage risk benchmark | 50.00%

X
- Definition Inverse correlation description. + References No definition available. + Details
Name: | ck0001415311_InverseCorrelationDescription
Namespace Prefix: | ck0001415311_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Definition Risk related to changes in benchmark interest rate approaching a specified percentage at any point in the day. + References No definition available. + Details
Name: | ck0001415311_PeriodPercentageThresholdRiskRelatedToChangesInBenchmarkInterestRate
Namespace Prefix: | ck0001415311_
Data Type: | num:percentItemType
Balance Type: | na
Period Type: | duration

X
- Definition Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table. + References No definition available. + Details
Name: | us-gaap_UnusualRiskOrUncertaintyLineItems
Namespace Prefix: | us-gaap_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Details
Name: | us-gaap_InvestmentTypeAxis=ck0001415311_UltraShortFundMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |