v3.10.0.1

Risk - Additional Information (Detail) | 6 Months Ended
--- | ---
Jun. 30, 2018
Unusual Risk or Uncertainty [Line Items] |
Percentage of calculation on simple inverse correlation | 200.00%
Ultrashort Fund [Member] |
Unusual Risk or Uncertainty [Line Items] |
Leverage risk benchmark | 50% at any point in the day
UltraPro Fund and UltraPro Short Fund [Member] |
Unusual Risk or Uncertainty [Line Items] |
Leverage risk benchmark | 33% at any point in the day

X
- Definition Percentage of calculation on simple inverse correlation. + References No definition available. + Details
Name: | ck0001415311_PercentageOfCalculationOnSimpleInverseCorrelation
Namespace Prefix: | ck0001415311_
Data Type: | num:percentItemType
Balance Type: | na
Period Type: | duration

X
- Definition Risk related to changes in benchmark interest rate. + References No definition available. + Details
Name: | ck0001415311_RiskRelatedToChangesInBenchmarkInterestRate
Namespace Prefix: | ck0001415311_
Data Type: | xbrli:stringItemType
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: |

X
- Details
Name: | us-gaap_InvestmentTypeAxis=ck0001415311_UltraProFundAndUltraProShortFundMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |