cm:Level2TextBlock: us-gaap:CertainLoansAndDebtSecuritiesAcquiredInTransferRecognizingInterestIncomeOnImpairedLoansPolicy
| Certain Loans and Debt Securities Acquired in Transfer, Recognizing Interest Income on Impaired Loans, Policy [Policy Text Block] |
| us-gaap:CertainLoansAndDebtSecuritiesAcquiredInTransferRecognizingInterestIncomeOnImpairedLoansPolicy |
| Disclosure of accounting policy for recognizing interest income on loans and 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 it is probable that the investor is unable to collect all cash flows expected at acquisition plus additional cash flows expected to be collected arising from changes in estimate after acquisition. |
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| us-gaap:CertainLoansAndDebtSecuritiesAcquiredInTransferRecognizingInterestIncomeOnImpairedLoansPolicy |