cm:Concept: us-gaap:PrincipalAssumptionsWhereAverageCostPerUnitIsUsed
| Principal Assumptions Where Average Cost Per Unit is Used |
| us-gaap:PrincipalAssumptionsWhereAverageCostPerUnitIsUsed |
| Principal assumptions, including total expected unit sales, units sold to date and units on order, underlying a total program or similar basis of accounting where estimated average cost per unit is used as a basis for removing cost from inventories. |
| cm:Concept |
| Text/String (xbrli:stringItemType) |
| For Period (duration) |
| (no balance type) |
| false |
| us-gaap:PrincipalAssumptionsWhereAverageCostPerUnitIsUsed |