cm:Member: us-gaap:FederalFundsPurchasedAndSecuritiesSoldUnderAgreementsToRepurchaseMember
| Federal Funds Purchased and Securities Sold under Agreements to Repurchase [Member] |
| us-gaap:FederalFundsPurchasedAndSecuritiesSoldUnderAgreementsToRepurchaseMember |
| Short term borrowing where a bank borrows, at the federal funds rate, from another bank and securities that an entity sells and agrees to repurchase at a specified date for a specified price. |
| cm:Member |
| [Member] (nonnum:domainItemType) |
| For Period (duration) |
| (no balance type) |
| true |
| us-gaap:FederalFundsPurchasedAndSecuritiesSoldUnderAgreementsToRepurchaseMember |