cm:Concept: us-gaap:IncreaseDecreaseCashCollateralFromCounterparties
| Increase (Decrease) Cash Collateral from Counterparties |
| us-gaap:IncreaseDecreaseCashCollateralFromCounterparties |
| The increase (decrease) during the reporting period in the amount of cash held either as collateral directly or provided to third parties associated with derivative instruments. Upon the occurrence of any specified triggering event or condition associated with the derivative, these amounts can be utilized to recover all or a portion of the amounts due or payable under the derivative. |
| cm:Concept |
| Monetary (xbrli:monetaryItemType) |
| For Period (duration) |
| Debit |
| false |
| us-gaap:IncreaseDecreaseCashCollateralFromCounterparties |