cm:Concept: us-gaap:AdditionalLiabilityLongDurationInsuranceCumulativeIncreaseDecreaseOfActualVarianceFromExpectedExperience
| Additional Liability, Long-Duration Insurance, Cumulative Increase (Decrease) of Actual Variance from Expected Experience |
| us-gaap:AdditionalLiabilityLongDurationInsuranceCumulativeIncreaseDecreaseOfActualVarianceFromExpectedExperience |
| Amount of cumulative increase (decrease) in present value of total expected payment to policyholder in excess of present value of total expected assessment from effect of variance from cash flow assumption change for actual experience. Excludes benefit classified as market risk benefit or under provisions of Topic 815 on derivative and hedging. |
| cm:Concept |
| Monetary (xbrli:monetaryItemType) |
| As Of (instant) |
| Credit |
| false |
| us-gaap:AdditionalLiabilityLongDurationInsuranceCumulativeIncreaseDecreaseOfActualVarianceFromExpectedExperience |