cm:Concept: us-gaap:LoansAndLeasesReceivableFeesEarnedButExcludedFromYield
| Loans and Leases Receivable, Fees Earned but Excluded from Yield |
| us-gaap:LoansAndLeasesReceivableFeesEarnedButExcludedFromYield |
| Reflects the amount of fees recognized as income related to loan originations, commitments or servicing which are not included in interest income and that exceed one percent of the aggregate of total interest income and other income. |
| cm:Concept |
| Monetary (xbrli:monetaryItemType) |
| For Period (duration) |
| Credit |
| false |
| us-gaap:LoansAndLeasesReceivableFeesEarnedButExcludedFromYield |