cm:Level3TextBlock: us-gaap:ScheduleOfSecuritiesFinancingTransactionsTextBlock
| Schedule of Securities Financing Transactions [Table Text Block] |
| us-gaap:ScheduleOfSecuritiesFinancingTransactionsTextBlock |
| Tabular disclosure of securities financing transactions including resale and repurchase agreements, securities borrowed and lending transactions, securities received as collateral and obligations to return securities received as collateral. |
| cm:Level3TextBlock |
| Text Block (HTML) (nonnum:textBlockItemType) |
| For Period (duration) |
| (no balance type) |
| false |
| us-gaap:ScheduleOfSecuritiesFinancingTransactionsTextBlock |