cm:Concept: us-gaap:AccountsReceivableUnapprovedContractClaimsAmountExpectedToBeCollectedWithinOneYear
| Accounts Receivable, Unapproved Contract Claims, Amount Expected to be Collected within One Year |
| us-gaap:AccountsReceivableUnapprovedContractClaimsAmountExpectedToBeCollectedWithinOneYear |
| The amount of unbilled receivables, which are expected to be collected within one year, from customers under long-term contracts that have not been billed and were not billable at the date of the statement of financial position. |
| cm:Concept |
| Monetary (xbrli:monetaryItemType) |
| As Of (instant) |
| Debit |
| false |
| us-gaap:AccountsReceivableUnapprovedContractClaimsAmountExpectedToBeCollectedWithinOneYear |