cm:Concept: us-gaap:DebtInstrumentIncreaseDecreaseForPeriodDescription
| Debt Instrument, Increase (Decrease) for Period, Description |
| us-gaap:DebtInstrumentIncreaseDecreaseForPeriodDescription |
| Description of the increases or decreases in the carrying amount of the debt instrument for the period, and may include a discussion of any significant changes in the authorized and issued amounts of bonds, mortgages and other types of debt during the reporting period. |
| cm:Concept |
| Text/String (xbrli:stringItemType) |
| For Period (duration) |
| (no balance type) |
| false |
| us-gaap:DebtInstrumentIncreaseDecreaseForPeriodDescription |