cm:Concept: us-gaap:SecuritiesPurchasedUnderAgreementsToResellOffsetAgainstCollateralNetOfNotSubjectToMasterNettingArrangementPolicyElection
| Securities Purchased under Agreements to Resell, Offset Against Collateral, Net of Not Subject to Master Netting Arrangement, Policy Election |
| us-gaap:SecuritiesPurchasedUnderAgreementsToResellOffsetAgainstCollateralNetOfNotSubjectToMasterNettingArrangementPolicyElection |
| Amount, after effects of master netting arrangements, deduction of assets not subject to a master netting arrangement and elected not to be offset, of funds outstanding loaned in the form of a security resale agreement between the entity and another party for the purchase and resale of identical or substantially the same securities at a date certain for a specified price, offset against an obligation to return collateral. |
| cm:Concept |
| Monetary (xbrli:monetaryItemType) |
| As Of (instant) |
| Debit |
| false |
| us-gaap:SecuritiesPurchasedUnderAgreementsToResellOffsetAgainstCollateralNetOfNotSubjectToMasterNettingArrangementPolicyElection |