cm:Concept: us-gaap:DerivativesUsedInNetInvestmentHedgeGainLossReclassifiedToEarningsNetOfTax
| Derivatives used in Net Investment Hedge, Gain (Loss), Reclassified to Earnings, Net of Tax |
| us-gaap:DerivativesUsedInNetInvestmentHedgeGainLossReclassifiedToEarningsNetOfTax |
| Amount, after tax, of reclassification from other comprehensive income (loss) to earnings from the sale or complete or substantially complete liquidation of an investment in a foreign entity. |
| cm:Concept |
| Monetary (xbrli:monetaryItemType) |
| For Period (duration) |
| Debit |
| false |
| us-gaap:DerivativesUsedInNetInvestmentHedgeGainLossReclassifiedToEarningsNetOfTax |