cm:Axis: us-gaap:DeferredCompensationArrangementWithIndividualShareBasedPaymentsByTypeOfDeferredCompensationAxis
| Equity-Based Arrangements, Individual Contracts, Type of Deferred Compensation [Axis] |
| us-gaap:DeferredCompensationArrangementWithIndividualShareBasedPaymentsByTypeOfDeferredCompensationAxis |
| Information by type of deferred compensation related to equity-based payment arrangements. Includes, but is not limited to, employment contracts with one or more selected officers or key employees. Excludes broad group equity-based compensation plans, defined benefit pension plans, defined benefit other postretirement benefit plans and other deferred compensation that is not equivalent to a defined benefit pension plan or a defined benefit other postretirement benefit plan. |
| cm:Axis |
| Text/String (xbrli:stringItemType) |
| For Period (duration) |
| (no balance type) |
| true |
| us-gaap:DeferredCompensationArrangementWithIndividualShareBasedPaymentsByTypeOfDeferredCompensationAxis |