cm:Concept: us-gaap:InventoryDescriptionUnpricedChangeOrdersForLongTermContractsOrProgram
| Inventory Description, Unpriced Change Orders for Long-term Contracts or Program |
| us-gaap:InventoryDescriptionUnpricedChangeOrdersForLongTermContractsOrProgram |
| Description of unpriced change orders or other similar items subject to uncertainty concerning their determination or ultimate realization included in inventory as of the balance sheet date and the status of principal items comprising such amount. |
| cm:Concept |
| Text/String (xbrli:stringItemType) |
| For Period (duration) |
| (no balance type) |
| false |
| us-gaap:InventoryDescriptionUnpricedChangeOrdersForLongTermContractsOrProgram |