cm:Concept: us-gaap:SecuritiesPurchasedUnderAgreementsToResellSetoffRightsDescription
| Securities Purchased under Agreements to Resell, Setoff Rights, Description |
| us-gaap:SecuritiesPurchasedUnderAgreementsToResellSetoffRightsDescription |
| Description of rights of setoff associated with the entity's recognized securities purchased under agreements to resell 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:SecuritiesPurchasedUnderAgreementsToResellSetoffRightsDescription |