cm:Concept: us-gaap:IncreaseDecreaseInOtherFinancialInstrumentsUsedInOperatingActivities
| Increase (Decrease) in Other Financial Instruments Used in Operating Activities |
| us-gaap:IncreaseDecreaseInOtherFinancialInstrumentsUsedInOperatingActivities |
| Amount of increase (decrease) in fair value of other financial instruments used in operating activities. |
| cm:Concept |
| Monetary (xbrli:monetaryItemType) |
| For Period (duration) |
| Credit |
| false |
| us-gaap:IncreaseDecreaseInOtherFinancialInstrumentsUsedInOperatingActivities |