cm:Concept: us-gaap:DescriptionOfDiscontinuationOfFairValueHedge
| Description of Discontinuation of Fair Value Hedge |
| us-gaap:DescriptionOfDiscontinuationOfFairValueHedge |
| Description of the method used to account for discontinued fair value hedge relationships, including identification of hedged items and hedging instruments. Includes reasons for the discontinuation of the fair value hedge and the effects of the discontinuation on the financial statements. |
| cm:Concept |
| Text/String (xbrli:stringItemType) |
| For Period (duration) |
| (no balance type) |
| false |
| us-gaap:DescriptionOfDiscontinuationOfFairValueHedge |