cm:Concept: us-gaap:ServicingLiabilityAtFairValueOtherChangesThatAffectBalance
| Servicing Liability at Fair Value, Other Changes that Affect Balance |
| us-gaap:ServicingLiabilityAtFairValueOtherChangesThatAffectBalance |
| Amount of increase (decrease) in fair value from changes classified as other for a contract to service financial assets under which the estimated future revenues from contractually specified servicing fees, late charges, and other ancillary revenues are not expected to adequately compensate the servicer. |
| cm:Concept |
| Monetary (xbrli:monetaryItemType) |
| For Period (duration) |
| Credit |
| false |
| us-gaap:ServicingLiabilityAtFairValueOtherChangesThatAffectBalance |