cm:Concept: us-gaap:AdditionalLiabilityLongDurationInsuranceOriginalDiscountRateBeforeCashFlowAndReinsurance
| Additional Liability, Long-Duration Insurance, Original Discount Rate, before Cash Flow and Reinsurance |
| us-gaap:AdditionalLiabilityLongDurationInsuranceOriginalDiscountRateBeforeCashFlowAndReinsurance |
| Amount, before effect of reinsurance and current period update of cash flow assumption, of present value of total expected payment to policyholder in excess of present value of total expected assessment, discounted at original rate. 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:AdditionalLiabilityLongDurationInsuranceOriginalDiscountRateBeforeCashFlowAndReinsurance |