cm:Concept: us-gaap:BusinessCombinationSeparatelyRecognizedTransactionsExpensesAndLossesRecognized
| Business Combination, Separately Recognized Transactions, Expenses and Losses Recognized |
| us-gaap:BusinessCombinationSeparatelyRecognizedTransactionsExpensesAndLossesRecognized |
| The expenses and losses recorded for each transaction with the acquiree that was recognized separately from the acquisition of assets and assumptions of liabilities in the business combination. |
| cm:Concept |
| Monetary (xbrli:monetaryItemType) |
| For Period (duration) |
| Debit |
| false |
| us-gaap:BusinessCombinationSeparatelyRecognizedTransactionsExpensesAndLossesRecognized |