cm:Level2TextBlock: us-gaap:DerivativesHedgeDiscontinuances
| Derivatives, Hedge Discontinuances [Policy Text Block] |
| us-gaap:DerivativesHedgeDiscontinuances |
| Disclosure of accounting policy for hedge discontinuances caused by termination of the hedging instrument, sale, extinguishment or maturity of the hedged item, or an assessment that it is no longer probable that an anticipated transaction will occur. |
| cm:Level2TextBlock |
| Text Block (HTML) (nonnum:textBlockItemType) |
| For Period (duration) |
| (no balance type) |
| false |
| us-gaap:DerivativesHedgeDiscontinuances |