cm:Concept: us-gaap:SecuritiesBorrowedOffsetAgainstCollateralNetOfNotSubjectToMasterNettingArrangementPolicyElection
| Securities Borrowed, Offset Against Collateral, Net of Not Subject to Master Netting Arrangement, Policy Election |
| us-gaap:SecuritiesBorrowedOffsetAgainstCollateralNetOfNotSubjectToMasterNettingArrangementPolicyElection |
| Amount, after effects of master netting arrangements, deduction of assets not subject to a master netting arrangement and elected not to be offset, of securities borrowed from entities in exchange for collateral, offset against an obligation to return collateral under a master netting arrangement. |
| cm:Concept |
| Monetary (xbrli:monetaryItemType) |
| As Of (instant) |
| Debit |
| false |
| us-gaap:SecuritiesBorrowedOffsetAgainstCollateralNetOfNotSubjectToMasterNettingArrangementPolicyElection |