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          | Open Option Contracts Written, Schedule of Investments [Table Text Block] | 
       
       
          
          | us-gaap:OpenOptionContractsWrittenScheduleOfInvestmentsTextBlock | 
       
       
          
          | Tabular disclosure of the information required in the supplementary schedule applicable to management investment companies listing written option contracts. | 
       
       
          
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          | Text Block (HTML) (nonnum:textBlockItemType) | 
       
       
          
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          | us-gaap:OpenOptionContractsWrittenScheduleOfInvestmentsTextBlock |