cm:Level3TextBlock: us-gaap:ContractWithCustomerAssetPastDueTableTextBlock
| Contract with Customer, Asset, Past Due [Table Text Block] |
| us-gaap:ContractWithCustomerAssetPastDueTableTextBlock |
| Tabular disclosure of aging analysis for right to consideration in exchange for good or service transferred to customer when right is conditioned on something other than passage of time. |
| cm:Level3TextBlock |
| Text Block (HTML) (nonnum:textBlockItemType) |
| For Period (duration) |
| (no balance type) |
| false |
| us-gaap:ContractWithCustomerAssetPastDueTableTextBlock |