cm:Level3TextBlock: us-gaap:FiniteLivedIntangibleAssetsAmortizationExpenseTableTextBlock
| Finite-lived Intangible Assets Amortization Expense [Table Text Block] |
| us-gaap:FiniteLivedIntangibleAssetsAmortizationExpenseTableTextBlock |
| Tabular disclosure of amortization expense of assets, excluding financial assets, that lack physical substance, having a limited useful life. |
| cm:Level3TextBlock |
| Text Block (HTML) (nonnum:textBlockItemType) |
| For Period (duration) |
| (no balance type) |
| false |
| us-gaap:FiniteLivedIntangibleAssetsAmortizationExpenseTableTextBlock |
| FiniteLivedIntangibleAssetsAmortizationExpense |