cm:Concept: us-gaap:InterestExpenseSecuritiesSoldUnderAgreementsToRepurchase
| Interest Expense, Securities Sold under Agreements to Repurchase |
| us-gaap:InterestExpenseSecuritiesSoldUnderAgreementsToRepurchase |
| Gross expenses on securities sold coupled with an agreement to repurchase the same from the same counterparty at a fixed or determinable price within a fixed or variable time period. |
| cm:Concept |
| Monetary (xbrli:monetaryItemType) |
| For Period (duration) |
| Debit |
| false |
| us-gaap:InterestExpenseSecuritiesSoldUnderAgreementsToRepurchase |