v3.21.1

Significant Accounting Policies - Additional Information (Detail) | 3 Months Ended
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Mar. 31, 2021
Minimum [Member] | Matching VIX Funds [Member] |
Significant Accounting Policies [Line Items] |
Percentage of brokerage commissions exceed variable create/redeem fees | 0.02%

X
- Definition Percentage of brokerage commissions exceed variable create/redeem fees. + References No definition available. + Details
Name: | ck0001415311_PercentageOfBrokerageCommissionsExceedVariableCreateOrRedeemFees
Namespace Prefix: | ck0001415311_
Data Type: | num:percentItemType
Balance Type: | na
Period Type: | duration

X
- Definition Significant accounting policies. + References No definition available. + Details
Name: | ck0001415311_SignificantAccountingPoliciesLineItems
Namespace Prefix: | ck0001415311_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Details
Name: | srt_RangeAxis=srt_MinimumMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_StatementBusinessSegmentsAxis=ck0001415311_MatchingVIXFundsMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |