v2.4.0.8

Risk - Additional Information (Detail) | 3 Months Ended
--- | ---
Mar. 31, 2014
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
Forward Agreements [Member] |
Unusual Risk or Uncertainty [Line Items] |
Exposure to swap agreements or forward contracts | 100.00%

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 Percentage of credit exposure. + References No definition available. + Details
Name: | ck0001415311_PercentageOfCreditExposure
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
- Details
Name: | us-gaap_UnusualRiskOrUncertaintyLineItems
Namespace Prefix: | us-gaap_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration