cm:Concept: us-gaap:AdjustmentsToAdditionalPaidInCapitalTaxEffectFromShareBasedCompensation
| Adjustments to Additional Paid in Capital, Income Tax Benefit from Share-based Compensation |
| us-gaap:AdjustmentsToAdditionalPaidInCapitalTaxEffectFromShareBasedCompensation |
| Amount of increase in additional paid in capital (APIC) resulting from a tax benefit associated with share-based compensation plan other than an employee stock ownership plan (ESOP). Includes, but is not limited to, excess tax benefit. |
| cm:Concept |
| Monetary (xbrli:monetaryItemType) |
| For Period (duration) |
| Credit |
| false |
| us-gaap:AdjustmentsToAdditionalPaidInCapitalTaxEffectFromShareBasedCompensation |