cm:Concept: us-gaap:LoansAndLeasesReceivableCommitmentsVariableRates
| Loans and Leases Receivable, Commitments, Variable Rates |
| us-gaap:LoansAndLeasesReceivableCommitmentsVariableRates |
| Reflects the amount of cash required to fully fund agreements to provide advances to borrowers and lessees at interest rates that increase or decrease depending on certain facts or circumstances. |
| cm:Concept |
| Monetary (xbrli:monetaryItemType) |
| For Period (duration) |
| Credit |
| false |
| us-gaap:LoansAndLeasesReceivableCommitmentsVariableRates |