cm:Concept: us-gaap:BusinessCombinationSeparatelyRecognizedTransactionsLiabilitiesRecognized
| Business Combination, Separately Recognized Transactions, Liabilities Recognized |
| us-gaap:BusinessCombinationSeparatelyRecognizedTransactionsLiabilitiesRecognized |
| The amount of liabilities recognized recorded in a transaction with the acquiree for each transaction 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) |
| Credit |
| false |
| us-gaap:BusinessCombinationSeparatelyRecognizedTransactionsLiabilitiesRecognized |