cm:Level1TextBlock: us-gaap:BusinessInsuranceRecoveriesTextBlock
| Business Insurance Recoveries [Text Block] |
| us-gaap:BusinessInsuranceRecoveriesTextBlock |
| The entire disclosure for business interruption insurance recoveries. Includes, but is not limited to, the nature of the event resulting in business interruption losses, amount of business interruption insurance recoveries recognized, and line item in the statement of income in which those recoveries are classified. |
| cm:Level1TextBlock |
| Text Block (HTML) (nonnum:textBlockItemType) |
| For Period (duration) |
| (no balance type) |
| false |
| us-gaap:BusinessInsuranceRecoveriesTextBlock |
| BusinessInsuranceRecoveriesDisclosure |