cm:Concept: us-gaap:ContractsReceivableClaimsAndUncertainAmountsNatureAndStatus
| Contracts Receivable, Claims and Uncertain Amounts, Nature and Status |
| us-gaap:ContractsReceivableClaimsAndUncertainAmountsNatureAndStatus |
| Explanation of the amounts included within receivables, billed or unbilled, under long-term contracts, which represent claims or other similar items subject to uncertainty concerning their determination or ultimate realization. |
| cm:Concept |
| Text/String (xbrli:stringItemType) |
| For Period (duration) |
| (no balance type) |
| false |
| us-gaap:ContractsReceivableClaimsAndUncertainAmountsNatureAndStatus |