cm:Concept: us-gaap:ContractWithCustomerLiabilityIncreaseDecreaseForContractAcquiredInBusinessCombination
| Contract with Customer, Liability, Increase (Decrease) for Contract Acquired in Business Combination |
| us-gaap:ContractWithCustomerLiabilityIncreaseDecreaseForContractAcquiredInBusinessCombination |
| Amount of increase (decrease) in obligation to transfer good or service to customer for which consideration from customer has been received or is due, from business combination. |
| cm:Concept |
| Monetary (xbrli:monetaryItemType) |
| For Period (duration) |
| Credit |
| false |
| us-gaap:ContractWithCustomerLiabilityIncreaseDecreaseForContractAcquiredInBusinessCombination |