cm:Concept: us-gaap:SecuritiesLoanedOrSoldUnderAgreementsToRepurchaseFairValueDisclosure
| Securities Loaned or Sold under Agreements to Repurchase, Fair Value Disclosure |
| us-gaap:SecuritiesLoanedOrSoldUnderAgreementsToRepurchaseFairValueDisclosure |
| Fair value portion of securities that an entity sells and agrees to repurchase at a specified date for a specified price. |
| cm:Concept |
| Monetary (xbrli:monetaryItemType) |
| As Of (instant) |
| Credit |
| false |
| us-gaap:SecuritiesLoanedOrSoldUnderAgreementsToRepurchaseFairValueDisclosure |