cm:Concept: us-gaap:BusinessCombinationSeparatelyRecognizedTransactionsAccountingMethod
| Business Combination, Separately Recognized Transactions, Accounting Method |
| us-gaap:BusinessCombinationSeparatelyRecognizedTransactionsAccountingMethod |
| A description of the accounting for each transaction that is recognized separately from the acquisition of assets and assumptions of liabilities in the business combination. |
| cm:Concept |
| Text/String (xbrli:stringItemType) |
| For Period (duration) |
| (no balance type) |
| false |
| us-gaap:BusinessCombinationSeparatelyRecognizedTransactionsAccountingMethod |