cm:Concept: us-gaap:DescriptionOfAccountingForDiscontinuationOfPriceRiskFairValueHedge
| Description of Accounting for Discontinuation of Price Risk Fair Value Hedge |
| us-gaap:DescriptionOfAccountingForDiscontinuationOfPriceRiskFairValueHedge |
| Description of the accounting for discontinuation of a price risk fair value hedging relationship. Includes the accounting for the hedged item and the hedging instrument after discontinuation of the hedge designation. Also includes discussion of income statement and balance sheet effects of the discontinuation and the method of amortization of any adjustments to the carrying value of hedged items (if applicable). |
| cm:Concept |
| Text/String (xbrli:stringItemType) |
| For Period (duration) |
| (no balance type) |
| false |
| us-gaap:DescriptionOfAccountingForDiscontinuationOfPriceRiskFairValueHedge |