cm:Concept: us-gaap:RevenuePracticalExpedientInitialApplicationAndTransitionQualitativeAssessment
| Revenue, Practical Expedient, Initial Application and Transition, Qualitative Assessment |
| us-gaap:RevenuePracticalExpedientInitialApplicationAndTransitionQualitativeAssessment |
| Description of assessment of estimated effect of practical expedients elected under initial application of retrospective method for completed contracts, completed contracts with variable consideration, modified contracts and disclosures of remaining performance obligation. |
| cm:Concept |
| Text/String (xbrli:stringItemType) |
| For Period (duration) |
| (no balance type) |
| false |
| us-gaap:RevenuePracticalExpedientInitialApplicationAndTransitionQualitativeAssessment |