cm:Level1TextBlock: us-gaap:AssetImpairmentChargesTextBlock
| Asset Impairment Charges [Text Block] |
| us-gaap:AssetImpairmentChargesTextBlock |
| The entire disclosure for the details of the charge against earnings resulting from the aggregate write down of all assets from their carrying value to their fair value. Disclosure may also include a description of the impaired asset and facts and circumstances leading to the impairment, amount of the impairment loss and where the loss is located in the income statement, method(s) for determining fair value, and the segment in which the impaired asset is reported. |
| cm:Level1TextBlock |
| Text Block (HTML) (nonnum:textBlockItemType) |
| For Period (duration) |
| (no balance type) |
| false |
| us-gaap:AssetImpairmentChargesTextBlock |
| AssetImpairmentCharges |