cm:Concept: us-gaap:GainContingencyDescription
| Gain Contingency, Description |
| us-gaap:GainContingencyDescription |
| Describes an existing condition, situation, or set of circumstances involving uncertainty as of the balance sheet date (or prior to issuance of the financial statements) as to a probable or reasonably possible gain to the entity that will ultimately be realized when one or more future events occur. |
| cm:Concept |
| Text/String (xbrli:stringItemType) |
| For Period (duration) |
| (no balance type) |
| false |
| us-gaap:GainContingencyDescription |