cm:Concept: us-gaap:AllCertainLoansAcquiredInTransferAccountedForAsAvailableForSaleDebtSecuritiesNotAccountedForUsingIncomeRecognitionModelAtCarryingValue
| All Certain Loans Acquired in Transfer Accounted for as Available-for-sale Debt Securities, Not Accounted for Using Income Recognition Model, at Carrying Value |
| us-gaap:AllCertainLoansAcquiredInTransferAccountedForAsAvailableForSaleDebtSecuritiesNotAccountedForUsingIncomeRecognitionModelAtCarryingValue |
| The recorded value of all loans accounted for as available-for-sale debt securities, with evidence of deterioration of credit quality since origination that were acquired by completion of a transfer for which it is probable, at acquisition, that the investor will be unable to collect all contractually required payments receivable, for which the income recognition model was not applied. |
| cm:Concept |
| Monetary (xbrli:monetaryItemType) |
| As Of (instant) |
| Debit |
| false |
| us-gaap:AllCertainLoansAcquiredInTransferAccountedForAsAvailableForSaleDebtSecuritiesNotAccountedForUsingIncomeRecognitionModelAtCarryingValue |