cm:Concept: us-gaap:SecuritiesSoldUnderAgreementsToRepurchaseSetoffRightsDescription
| Securities Sold under Agreements to Repurchase, Setoff Rights, Description |
| us-gaap:SecuritiesSoldUnderAgreementsToRepurchaseSetoffRightsDescription |
| Description of rights of setoff associated with the entity's recognized securities sold under agreements to repurchase subject to an enforceable master netting arrangement or similar agreement. |
| cm:Concept |
| Text/String (xbrli:stringItemType) |
| For Period (duration) |
| (no balance type) |
| false |
| us-gaap:SecuritiesSoldUnderAgreementsToRepurchaseSetoffRightsDescription |