cm:Concept: us-gaap:SecuritiesPurchasedUnderAgreementsToResellLiability
| Securities Purchased under Agreements to Resell, Liability |
| us-gaap:SecuritiesPurchasedUnderAgreementsToResellLiability |
| Amount of liability associated with 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. |
| cm:Concept |
| Monetary (xbrli:monetaryItemType) |
| As Of (instant) |
| Credit |
| false |
| us-gaap:SecuritiesPurchasedUnderAgreementsToResellLiability |