cm:Concept: us-gaap:DerivativeInstrumentsIncomeStatementLocationOfGainOrLossReclassifiedFromAccumulatedOCI
| Derivative Instruments, Income Statement Location of Gain (Loss) Reclassified from Accumulated OCI |
| us-gaap:DerivativeInstrumentsIncomeStatementLocationOfGainOrLossReclassifiedFromAccumulatedOCI |
| The income statement location of the effective portion of net gain (loss) reclassified from accumulated other comprehensive income into income on derivative instruments designated and qualifying as hedging instruments. |
| cm:Concept |
| Text/String (xbrli:stringItemType) |
| For Period (duration) |
| (no balance type) |
| false |
| us-gaap:DerivativeInstrumentsIncomeStatementLocationOfGainOrLossReclassifiedFromAccumulatedOCI |