cm:Level2TextBlock: us-gaap:InterestInUnincorporatedJointVenturesOrPartnershipsPolicy
| Interest in Unincorporated Joint Ventures or Partnerships, Policy [Policy Text Block] |
| us-gaap:InterestInUnincorporatedJointVenturesOrPartnershipsPolicy |
| Disclosure of accounting policy for interest in an unincorporated joint venture or partnership that is included in the enterprise's financial statements using the proportionate consolidation method of accounting. |
| cm:Level2TextBlock |
| Text Block (HTML) (nonnum:textBlockItemType) |
| For Period (duration) |
| (no balance type) |
| false |
| us-gaap:InterestInUnincorporatedJointVenturesOrPartnershipsPolicy |