cm:Concept: us-gaap:CertainLoansAcquiredInTransferAccountedForAsHeldToMaturityDebtSecuritiesCarryingAmountNet
| Certain Loans Acquired in Transfer Accounted for as Held-to-maturity Debt Securities, Carrying Amount, Net |
| us-gaap:CertainLoansAcquiredInTransferAccountedForAsHeldToMaturityDebtSecuritiesCarryingAmountNet |
| The recorded balance, net of any applicable reductions (for example, unamortized accretable yield and other-than-temporary impairments), for certain contractual rights to receive money on demand or on fixed or determinable dates. This relates to loans accounted for as held-to-maturity 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. |
| cm:Concept |
| Monetary (xbrli:monetaryItemType) |
| As Of (instant) |
| Debit |
| false |
| us-gaap:CertainLoansAcquiredInTransferAccountedForAsHeldToMaturityDebtSecuritiesCarryingAmountNet |