cm:Level3TextBlock: us-gaap:OpenOptionContractsWrittenScheduleOfInvestmentsTextBlock
| 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. |
| cm:Level3TextBlock |
| Text Block (HTML) (nonnum:textBlockItemType) |
| For Period (duration) |
| (no balance type) |
| false |
| us-gaap:OpenOptionContractsWrittenScheduleOfInvestmentsTextBlock |