cm:Level2TextBlock: us-gaap:GuaranteesIndemnificationsAndWarrantiesPolicies
| Guarantees, Indemnifications and Warranties Policies [Policy Text Block] |
| us-gaap:GuaranteesIndemnificationsAndWarrantiesPolicies |
| Disclosure of accounting policy for guarantees, indemnifications and product warranties, and methodologies used in determining the amount of such liabilities. |
| cm:Level2TextBlock |
| Text Block (HTML) (nonnum:textBlockItemType) |
| For Period (duration) |
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| us-gaap:GuaranteesIndemnificationsAndWarrantiesPolicies |