cm:Concept: us-gaap:InventoryAmountUnpricedChangeOrdersForLongTermContractsOrPrograms
       
          
          | Inventory Amount, Unpriced Change Orders for Long-term Contracts or Programs | 
       
       
          
          | us-gaap:InventoryAmountUnpricedChangeOrdersForLongTermContractsOrPrograms | 
       
       
          
          | Amount 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. | 
       
       
          
          | cm:Concept | 
       
       
          
          | Monetary (xbrli:monetaryItemType) | 
       
       
          
          | As Of (instant) | 
       
       
          
          | Debit | 
       
       
          
          | false | 
       
       
          
          | us-gaap:InventoryAmountUnpricedChangeOrdersForLongTermContractsOrPrograms |