cm:Concept: us-gaap:DescriptionOfAccountingMethodUsedForPriceRiskDerivatives
| Description of Accounting Method Used for Price Risk Derivatives |
| us-gaap:DescriptionOfAccountingMethodUsedForPriceRiskDerivatives |
| General discussion of the accounting for price risk derivatives. Includes discussion of where derivatives and the gain (loss) on derivatives are reported in the financial statements. Also includes discussion of any hedge designations used, the assessment of hedge effectiveness and measurement of hedge ineffectiveness. |
| cm:Concept |
| Text/String (xbrli:stringItemType) |
| For Period (duration) |
| (no balance type) |
| false |
| us-gaap:DescriptionOfAccountingMethodUsedForPriceRiskDerivatives |