cm:Concept: us-gaap:BusinessCombinationSeparatelyRecognizedTransactionsAssetsRecognized
| Business Combination, Separately Recognized Transactions, Assets Recognized |
| us-gaap:BusinessCombinationSeparatelyRecognizedTransactionsAssetsRecognized |
| The assets recognized for each amount of assets recorded in a transaction with the acquiree that is recognized separately from the acquisition of assets and assumptions of liabilities in the business combination. |
| cm:Concept |
| Monetary (xbrli:monetaryItemType) |
| As Of (instant) |
| Debit |
| false |
| us-gaap:BusinessCombinationSeparatelyRecognizedTransactionsAssetsRecognized |