cm:Concept: us-gaap:SecuritiesOwnedAndPledgedAsCollateralDescription
| Securities Owned and Pledged as Collateral, Description |
| us-gaap:SecuritiesOwnedAndPledgedAsCollateralDescription |
| Description 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:Concept |
| Text/String (xbrli:stringItemType) |
| For Period (duration) |
| (no balance type) |
| false |
| us-gaap:SecuritiesOwnedAndPledgedAsCollateralDescription |