cm:Concept: us-gaap:UnrealizedGainOnPriceRiskCashFlowDerivativesBeforeTax
| Unrealized Gain on Price Risk Cash Flow Derivatives, before Tax |
| us-gaap:UnrealizedGainOnPriceRiskCashFlowDerivativesBeforeTax |
| Amount of unrealized gain from the increase in fair value of price risk derivatives designated as cash flow hedging instruments recorded in accumulated other comprehensive income in the period, before taxes, to the extent that the cash flow hedge is determined to be effective. |
| cm:Concept |
| Monetary (xbrli:monetaryItemType) |
| For Period (duration) |
| Credit |
| false |
| us-gaap:UnrealizedGainOnPriceRiskCashFlowDerivativesBeforeTax |