cm:Concept: us-gaap:RepaymentsOfSubordinatedShortTermDebt
| Repayments of Subordinated Short-term Debt |
| us-gaap:RepaymentsOfSubordinatedShortTermDebt |
| The cash outflow for an obligation which places a lender in a lien position behind debt having a higher priority of repayment (senior loan) in liquidation of the entity's assets scheduled to be repaid within one year or in the normal operating cycle of the entity, if longer. |
| cm:Concept |
| Monetary (xbrli:monetaryItemType) |
| For Period (duration) |
| Credit |
| false |
| us-gaap:RepaymentsOfSubordinatedShortTermDebt |