cm:Level2TextBlock: us-gaap:DerivativesHedgeDiscontinuancesAnticipatedTransactions
| Derivatives, Hedge Discontinuances, Anticipated Transactions [Policy Text Block] |
| us-gaap:DerivativesHedgeDiscontinuancesAnticipatedTransactions |
| Disclosure of accounting policy for derivatives designated to an anticipated transaction, when it is no longer probable that the anticipated transaction will occur. |
| cm:Level2TextBlock |
| Text Block (HTML) (nonnum:textBlockItemType) |
| For Period (duration) |
| (no balance type) |
| false |
| us-gaap:DerivativesHedgeDiscontinuancesAnticipatedTransactions |