cm:Level3TextBlock: us-gaap:ScheduleOfFinancialInstrumentsOwnedAndPledgedAsCollateralTextBlock
| Schedule of Financial Instruments Owned and Pledged as Collateral [Table Text Block] |
| us-gaap:ScheduleOfFinancialInstrumentsOwnedAndPledgedAsCollateralTextBlock |
| Tabular disclosure of financial instruments held by the entity for its own account for trading or investment purposes that are carried at fair value and pledged to counterparties as collateral for financing transactions. Description may include equity, fixed income, debt or other securities. |
| cm:Level3TextBlock |
| Text Block (HTML) (nonnum:textBlockItemType) |
| For Period (duration) |
| (no balance type) |
| false |
| us-gaap:ScheduleOfFinancialInstrumentsOwnedAndPledgedAsCollateralTextBlock |