cm:Concept: us-gaap:TransfersOfFinancialAssetsAccountedForAsSaleInitialFairValueOfAssetsObtainedAsProceeds
| Transfers of Financial Assets Accounted for as Sale, Initial Fair Value of Assets Obtained as Proceeds |
| us-gaap:TransfersOfFinancialAssetsAccountedForAsSaleInitialFairValueOfAssetsObtainedAsProceeds |
| Represents the initial fair value recorded for assets received 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) |
| Debit |
| false |
| us-gaap:TransfersOfFinancialAssetsAccountedForAsSaleInitialFairValueOfAssetsObtainedAsProceeds |