cm:Concept: us-gaap:PostemploymentBenefitsLiabilityNoncurrent
| Postemployment Benefits Liability, Noncurrent |
| us-gaap:PostemploymentBenefitsLiabilityNoncurrent |
| For a classified balance sheet, the carrying amount as of the balance sheet date of the portion of the obligations recognized for the various benefits provided to former or inactive employees, their beneficiaries, and covered dependents after employment but before retirement that is payable after one year (or beyond the operating cycle if longer). |
| cm:Concept |
| Monetary (xbrli:monetaryItemType) |
| As Of (instant) |
| Credit |
| false |
| us-gaap:PostemploymentBenefitsLiabilityNoncurrent |