cm:Concept: us-gaap:UndistributedContinuingOperationEarningsLossBasic
| Undistributed Continuing Operation Earnings (Loss), Basic |
| us-gaap:UndistributedContinuingOperationEarningsLossBasic |
| Amount of undistributed earnings (loss) from continuing operations, allocated to common stock and participating securities, as if earnings had been distributed. Excludes distributed earnings. |
| cm:Concept |
| Monetary (xbrli:monetaryItemType) |
| For Period (duration) |
| Credit |
| false |
| us-gaap:UndistributedContinuingOperationEarningsLossBasic |