cm:Concept: us-gaap:ForeignCurrencyCashFlowHedgeGainLossReclassifiedToEarningsNet
| Foreign Currency Cash Flow Hedge Gain (Loss) Reclassified to Earnings, Net |
| us-gaap:ForeignCurrencyCashFlowHedgeGainLossReclassifiedToEarningsNet |
| The amount of net gains or losses on foreign currency cash flow hedges reclassified during the period to earnings from accumulated other comprehensive income upon the hedged transaction affecting earnings. |
| cm:Concept |
| Monetary (xbrli:monetaryItemType) |
| For Period (duration) |
| Credit |
| false |
| us-gaap:ForeignCurrencyCashFlowHedgeGainLossReclassifiedToEarningsNet |