cm:Concept: us-gaap:CertainLoansAcquiredInTransferAccountedForAsHeldToMaturityDebtSecuritiesAcquiredDuringPeriodNotAccountedForUsingIncomeRecognitionModelAtAcquisitionAtCarryingValue
| Certain Loans Acquired in Transfer Accounted for as Held-to-maturity Debt Securities, Acquired During Period, Not Accounted for Using Income Recognition Model, at Acquisition, at Carrying Value |
| us-gaap:CertainLoansAcquiredInTransferAccountedForAsHeldToMaturityDebtSecuritiesAcquiredDuringPeriodNotAccountedForUsingIncomeRecognitionModelAtAcquisitionAtCarryingValue |
| The recorded value, at the acquisition date, of loans accounted for as held-to-maturity debt securities acquired during the period, 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:CertainLoansAcquiredInTransferAccountedForAsHeldToMaturityDebtSecuritiesAcquiredDuringPeriodNotAccountedForUsingIncomeRecognitionModelAtAcquisitionAtCarryingValue |