cm:Concept: us-gaap:RetentionPayableDueAfterOneYear
| Retention Payable, Due after One Year |
| us-gaap:RetentionPayableDueAfterOneYear |
| Amounts owed to vendors and subcontractors that have been withheld because of retainage provisions in a contract to be paid after the next fiscal year following the latest fiscal year. Excludes 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:RetentionPayableDueAfterOneYear |