cm:Concept: us-gaap:ContractWithCustomerAssetIncreaseDecreaseForContractAcquiredInBusinessCombination
| Contract with Customer, Asset, Increase (Decrease) for Contract Acquired in Business Combination |
| us-gaap:ContractWithCustomerAssetIncreaseDecreaseForContractAcquiredInBusinessCombination |
| Amount of increase (decrease) in right to consideration in exchange for good or service transferred to customer when right is conditioned on something other than passage of time, from business combination. |
| cm:Concept |
| Monetary (xbrli:monetaryItemType) |
| For Period (duration) |
| Debit |
| false |
| us-gaap:ContractWithCustomerAssetIncreaseDecreaseForContractAcquiredInBusinessCombination |