cm:Level2TextBlock: us-gaap:RevenueRecognitionRevenueReductions
| Revenue Recognition, Revenue Reductions [Policy Text Block] |
| us-gaap:RevenueRecognitionRevenueReductions |
| Disclosure of accounting policy of sales arrangements for goods or services that reduce the amount of revenue recognized for example sales returns, allowances, incentives, rebates, discounts and loyalty programs. |
| cm:Level2TextBlock |
| Text Block (HTML) (nonnum:textBlockItemType) |
| For Period (duration) |
| (no balance type) |
| false |
| us-gaap:RevenueRecognitionRevenueReductions |