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