cm:Member: us-gaap:SecuritiesLoanedOrSoldUnderAgreementsToRepurchaseMember
| Securities Loaned or Sold under Agreements to Repurchase [Member] |
| us-gaap:SecuritiesLoanedOrSoldUnderAgreementsToRepurchaseMember |
| The amount of securities that an institution sells and agrees to repurchase at a specified date for a specified price, net of any reductions or offsets. |
| cm:Member |
| [Member] (nonnum:domainItemType) |
| For Period (duration) |
| (no balance type) |
| true |
| us-gaap:SecuritiesLoanedOrSoldUnderAgreementsToRepurchaseMember |