cm:Level3TextBlock: us-gaap:FairValueAssetsAndLiabilitiesMeasuredOnRecurringBasisGainLossIncludedInEarningsTextBlock
| Fair Value, Measured on Recurring Basis, Gain (Loss) Included in Earnings [Table Text Block] |
| us-gaap:FairValueAssetsAndLiabilitiesMeasuredOnRecurringBasisGainLossIncludedInEarningsTextBlock |
| Tabular disclosure of the amount of gains or losses for the period included in earnings or resulted in a change to net assets, have arisen from the use of significant unobservable inputs (level 3) to measure the fair value of assets, liabilities, and financial instruments classified in shareholders' equity. |
| cm:Level3TextBlock |
| Text Block (HTML) (nonnum:textBlockItemType) |
| For Period (duration) |
| (no balance type) |
| false |
| us-gaap:FairValueAssetsAndLiabilitiesMeasuredOnRecurringBasisGainLossIncludedInEarningsTextBlock |