cm:Concept: us-gaap:DiscontinuedOperationGainLossOnDisposalOfDiscontinuedOperationNetOfTaxPerBasicAndDilutedShare
| Discontinued Operation, Gain (Loss) on Disposal of Discontinued Operation, Net of Tax, Per Basic and Diluted Share |
| us-gaap:DiscontinuedOperationGainLossOnDisposalOfDiscontinuedOperationNetOfTaxPerBasicAndDilutedShare |
| Per basic and diluted share amount, after tax, of the gain (loss) on the disposal of discontinued operations, when the per share amount is the same. |
| cm:Concept |
| Share (num:perShareItemType) |
| For Period (duration) |
| (no balance type) |
| false |
| us-gaap:DiscontinuedOperationGainLossOnDisposalOfDiscontinuedOperationNetOfTaxPerBasicAndDilutedShare |