cm:Concept: us-gaap:InterestAccrualRateAssociatedWithAmortizationMethodOfPresentValueOfFutureInsuranceProfits
| Interest Accrual Rate Associated with Amortization Method of Present Value of Future Insurance Profits |
| us-gaap:InterestAccrualRateAssociatedWithAmortizationMethodOfPresentValueOfFutureInsuranceProfits |
| Rate of interest used in determination of present value of future profits on insurance contract acquired in business combination. |
| cm:Concept |
| Percent (num:percentItemType) |
| For Period (duration) |
| (no balance type) |
| false |
| us-gaap:InterestAccrualRateAssociatedWithAmortizationMethodOfPresentValueOfFutureInsuranceProfits |