cm:Concept: us-gaap:DebtSecuritiesAvailableForSaleMaturityRollingAfter10YearsWeightedAverageYield
| Debt Securities, Available-for-sale, Maturity, Rolling after 10 Years, Weighted Average Yield |
| us-gaap:DebtSecuritiesAvailableForSaleMaturityRollingAfter10YearsWeightedAverageYield |
| Weighted average yield of investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale), maturing after tenth rolling fiscal year following latest fiscal year. For interim and annual periods when interim period is reported on rolling approach, from latest statement of financial position date. |
| cm:Concept |
| Percent (num:percentItemType) |
| As Of (instant) |
| (no balance type) |
| false |
| us-gaap:DebtSecuritiesAvailableForSaleMaturityRollingAfter10YearsWeightedAverageYield |