cm:Concept: us-gaap:TransfersOfFinancialAssetsAccountedForAsSaleInitialFairValueOfLiabilitiesIncurred
| Transfers of Financial Assets Accounted for as Sale, Initial Fair Value of Liabilities Incurred |
| us-gaap:TransfersOfFinancialAssetsAccountedForAsSaleInitialFairValueOfLiabilitiesIncurred |
| Represents the initial fair value recorded for liabilities incurred on transfer of financial assets in a securitization, asset-backed financing arrangement, or a similar transfer which transaction is recognized as a sale of the transferred financial assets. |
| cm:Concept |
| Monetary (xbrli:monetaryItemType) |
| As Of (instant) |
| Credit |
| false |
| us-gaap:TransfersOfFinancialAssetsAccountedForAsSaleInitialFairValueOfLiabilitiesIncurred |