cm:Level3TextBlock: us-gaap:ScheduleOfPrincipalTransactionsRevenueTextBlock
| Schedule of Principal Transactions Revenue [Table Text Block] |
| us-gaap:ScheduleOfPrincipalTransactionsRevenueTextBlock |
| Tabular disclosure of revenue by reporting categories or types of financial instruments, including derivatives but excluding dividends and interests, from trading for own account by broker dealers. |
| cm:Level3TextBlock |
| Text Block (HTML) (nonnum:textBlockItemType) |
| For Period (duration) |
| (no balance type) |
| false |
| us-gaap:ScheduleOfPrincipalTransactionsRevenueTextBlock |