cm:Level2TextBlock: us-gaap:DerivativesMethodsOfAccountingHedgingDerivatives
| Derivatives, Methods of Accounting, Hedging Derivatives [Policy Text Block] |
| us-gaap:DerivativesMethodsOfAccountingHedgingDerivatives |
| Disclosure of accounting policy for derivatives used in hedging relationships, which may include how gains or losses are recognized and presented in the financial statements, and amortization policies for deferred amounts. |
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| Text Block (HTML) (nonnum:textBlockItemType) |
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| us-gaap:DerivativesMethodsOfAccountingHedgingDerivatives |