cm:Level3TextBlock: us-gaap:ScheduleOfGainLossOnSecuritizationsOfFinancialAssetsAccountedForAsSaleTextBlock
| Schedule of Gain (Loss) on Securitizations or Asset-backed Financing Arrangements of Financial Assets Accounted for as Sale [Table Text Block] |
| us-gaap:ScheduleOfGainLossOnSecuritizationsOfFinancialAssetsAccountedForAsSaleTextBlock |
| Tabular disclosure of amounts pertaining to the excess over or deficiency from the carrying amounts of financial assets which are recognized upon the sale of financial assets. |
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| Text Block (HTML) (nonnum:textBlockItemType) |
| For Period (duration) |
| (no balance type) |
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| us-gaap:ScheduleOfGainLossOnSecuritizationsOfFinancialAssetsAccountedForAsSaleTextBlock |