cm:Level2TextBlock: us-gaap:SharesSubjectToMandatoryRedemptionChangesInRedemptionValuePolicyTextBlock
| Shares Subject to Mandatory Redemption, Changes in Redemption Value, Policy [Policy Text Block] |
| us-gaap:SharesSubjectToMandatoryRedemptionChangesInRedemptionValuePolicyTextBlock |
| Disclosure of accounting policy for recognition of changes in redemption value of mandatorily redeemable shares. Provides the period over which changes in redemption value are accreted, usually from the issuance date (or from the date that it becomes probable that the security will become redeemable, if later) to the earliest redemption date of the security. |
| cm:Level2TextBlock |
| Text Block (HTML) (nonnum:textBlockItemType) |
| For Period (duration) |
| (no balance type) |
| false |
| us-gaap:SharesSubjectToMandatoryRedemptionChangesInRedemptionValuePolicyTextBlock |