cm:Concept: us-gaap:LongtermDebtPercentageBearingVariableInterestAmount
| Long-term Debt, Percentage Bearing Variable Interest, Amount |
| us-gaap:LongtermDebtPercentageBearingVariableInterestAmount |
| The portion of the carrying amount of long-term borrowings outstanding as of the balance sheet date, including current maturities, which accrues interest at a rate subject to change from time to time. |
| cm:Concept |
| Monetary (xbrli:monetaryItemType) |
| As Of (instant) |
| Credit |
| false |
| us-gaap:LongtermDebtPercentageBearingVariableInterestAmount |