cm:Member: us-gaap:BusinessCombinationSeparatelyRecognizedTransactionsDomain
| Business Combination, Separately Recognized Transactions [Domain] |
| us-gaap:BusinessCombinationSeparatelyRecognizedTransactionsDomain |
| Type of transaction that is recognized separately from the acquisition of assets and assumptions of liabilities in a business combination by transaction. |
| cm:Member |
| [Member] (nonnum:domainItemType) |
| For Period (duration) |
| (no balance type) |
| true |
| us-gaap:BusinessCombinationSeparatelyRecognizedTransactionsDomain |