cm:Concept: us-gaap:ConsiderationReceivedForBeneficialInterestObtainedForTransferringFinancialAsset
| Consideration Received for Beneficial Interest Obtained for Transferring Financial Asset |
| us-gaap:ConsiderationReceivedForBeneficialInterestObtainedForTransferringFinancialAsset |
| Amount of beneficial interest received as consideration for transferring noncash financial asset. Includes, but is not limited to, trade receivable in securitization transaction. |
| cm:Concept |
| Monetary (xbrli:monetaryItemType) |
| For Period (duration) |
| Debit |
| false |
| us-gaap:ConsiderationReceivedForBeneficialInterestObtainedForTransferringFinancialAsset |