cm:Level2TextBlock: us-gaap:LoansAndLeasesReceivableOriginationFeesDiscountsOrPremiumsAndDirectCostsToAcquireLoansPolicy
| Financing Receivable, Fee and Interest Income [Policy Text Block] |
| us-gaap:LoansAndLeasesReceivableOriginationFeesDiscountsOrPremiumsAndDirectCostsToAcquireLoansPolicy |
| Disclosure of accounting policy for method for recognizing interest income and amortizing deferred fee or cost of financing receivable. Includes, but is not limited to, treatment of fee, cost, premium and discount. |
| cm:Level2TextBlock |
| Text Block (HTML) (nonnum:textBlockItemType) |
| For Period (duration) |
| (no balance type) |
| false |
| us-gaap:LoansAndLeasesReceivableOriginationFeesDiscountsOrPremiumsAndDirectCostsToAcquireLoansPolicy |