cm:Level1TextBlock: us-gaap:DebtInstrumentRedemptionTableTextBlock
| Debt Instrument Redemption [Table Text Block] |
| us-gaap:DebtInstrumentRedemptionTableTextBlock |
| Tabular disclosure of debt instruments or arrangements with redemption features. Includes, but is not limited to, description of debt redemption features, percentage price at which debt can be redeemed by the issuer, and period start and end for debt maturity or redemption. |
| cm:Level1TextBlock |
| Text Block (HTML) (nonnum:textBlockItemType) |
| For Period (duration) |
| (no balance type) |
| false |
| us-gaap:DebtInstrumentRedemptionTableTextBlock |
| DebtInstrumentRedemptionDisclosure |