cm:Level3TextBlock: us-gaap:ScheduleOfSensitivityAnalysisOfFairValueOfInterestsContinuedToBeHeldByTransferorServicingAssetsOrServicingLiabilitiesTextBlock
| Schedule of Sensitivity Analysis of Fair Value, Transferor's Interests in Transferred Financial Assets [Table Text Block] |
| us-gaap:ScheduleOfSensitivityAnalysisOfFairValueOfInterestsContinuedToBeHeldByTransferorServicingAssetsOrServicingLiabilitiesTextBlock |
| Tabular disclosure of a sensitivity analysis or stress test showing the hypothetical effect on the fair value of the transferor's interests in transferred financial assets (including any servicing assets or servicing liabilities) of two or more unfavorable variations from the expected levels for each key assumption that is reported, independently determined from any change in another key assumption, and a description of the objectives, methodology, and limitations of the sensitivity analysis or stress test. |
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| us-gaap:ScheduleOfSensitivityAnalysisOfFairValueOfInterestsContinuedToBeHeldByTransferorServicingAssetsOrServicingLiabilitiesTextBlock |