cm:Concept: us-gaap:SecuritiesBorrowedGrossIncludingNotSubjectToMasterNettingArrangement
| Securities Borrowed, Gross Including Not Subject to Master Netting Arrangement |
| us-gaap:SecuritiesBorrowedGrossIncludingNotSubjectToMasterNettingArrangement |
| Amount, before effects of master netting arrangements, of securities borrowed from entities in exchange for collateral. Includes assets not subject to a master netting arrangement and elected not to be offset. |
| cm:Concept |
| Monetary (xbrli:monetaryItemType) |
| As Of (instant) |
| Debit |
| false |
| us-gaap:SecuritiesBorrowedGrossIncludingNotSubjectToMasterNettingArrangement |