cm:Concept: us-gaap:ContractWithCustomerPerformanceObligationSatisfiedInPreviousPeriod
| Contract with Customer, Performance Obligation Satisfied in Previous Period |
| us-gaap:ContractWithCustomerPerformanceObligationSatisfiedInPreviousPeriod |
| Amount of revenue recognized from performance obligation satisfied or partially satisfied in previous reporting periods. Includes, but is not limited to, change in transaction price. |
| cm:Concept |
| Monetary (xbrli:monetaryItemType) |
| For Period (duration) |
| Credit |
| false |
| us-gaap:ContractWithCustomerPerformanceObligationSatisfiedInPreviousPeriod |