cm:Level2TextBlock: us-gaap:LoansAndLeasesReceivableNonperformingLoanAndLeasePolicy
| Loans and Leases Receivable, Nonperforming Loan and Lease, Policy [Policy Text Block] |
| us-gaap:LoansAndLeasesReceivableNonperformingLoanAndLeasePolicy |
| Disclosure of accounting policy for deeming amounts due from a borrower as not being in compliance with principal and interest payment terms, describes the method for valuing a loan in such status, and indicates whether interest contractually accruing thereon is being recognized as income. |
| cm:Level2TextBlock |
| Text Block (HTML) (nonnum:textBlockItemType) |
| For Period (duration) |
| (no balance type) |
| false |
| us-gaap:LoansAndLeasesReceivableNonperformingLoanAndLeasePolicy |