cm:Concept: us-gaap:BusinessCombinationIndemnificationAssetsRangeOfOutcomesInestimable
| Business Combination, Indemnification Assets, Range of Outcomes, Inestimable |
| us-gaap:BusinessCombinationIndemnificationAssetsRangeOfOutcomesInestimable |
| For indemnification assets recognized in connection with a business combination, if a range (undiscounted) of potential outcomes cannot be estimated, this element represents a statement of that fact and the reasons why a range cannot be estimated. |
| cm:Concept |
| Text/String (xbrli:stringItemType) |
| For Period (duration) |
| (no balance type) |
| false |
| us-gaap:BusinessCombinationIndemnificationAssetsRangeOfOutcomesInestimable |