cm:Concept: us-gaap:RetentionPayableDueInRollingYearThree
| Retention Payable, Due in Rolling Year Three |
| us-gaap:RetentionPayableDueInRollingYearThree |
| Amounts owed to vendors and subcontractors that have been withheld because of retainage provisions in a contract to be paid in the third rolling twelve months following the latest balance sheet. For interim and annual periods when interim periods are reported on a rolling approach, from latest balance sheet date. |
| cm:Concept |
| Monetary (xbrli:monetaryItemType) |
| As Of (instant) |
| Credit |
| false |
| us-gaap:RetentionPayableDueInRollingYearThree |