cm:Concept: us-gaap:ProceedsFromMaturitiesPrepaymentsAndCallsOfOtherInvestments
| Proceeds from Maturities, Prepayments and Calls of Other Investments |
| us-gaap:ProceedsFromMaturitiesPrepaymentsAndCallsOfOtherInvestments |
| The cash inflow associated with the maturity (principal being due), prepayment and call (request of early payment) of other investments not otherwise defined in the taxonomy. |
| cm:Concept |
| Monetary (xbrli:monetaryItemType) |
| For Period (duration) |
| Debit |
| false |
| us-gaap:ProceedsFromMaturitiesPrepaymentsAndCallsOfOtherInvestments |