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Summary of Significant Accounting Policies (Additional Information) (Details) | 12 Months Ended
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Dec. 31, 2015 $ / Units
Significant Accounting Policies [Line Items] |
Fee paid by Authorized Purchasers for each order placed to create one or more Creation Baskets or to redeem one or more baskets | 350
Creation Baskets |
Significant Accounting Policies [Line Items] |
Number of Shares per basket | 50,000
Prior to July 1, 2011 |
Significant Accounting Policies [Line Items] |
Fee paid by Authorized Purchasers for each order placed to create one or more Creation Baskets or to redeem one or more baskets | 1,000
Maximum |
Significant Accounting Policies [Line Items] |
Cash equivalents maturity period | 6 months

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