Creation and Redemption of Creation Units - Additional Information (Detail) |
9 Months Ended |
|---|---|
|
Sep. 30, 2017
$ / 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 | 500 |
| 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% |