cm:Level2TextBlock: us-gaap:ContingentLiabilityReserveEstimatePolicy
| Contingent Liability Reserve Estimate, Policy [Policy Text Block] |
| us-gaap:ContingentLiabilityReserveEstimatePolicy |
| Disclosure of accounting policy for the claims loss reserve for insurance contracts with a life contingency (permanent life, some term life, accident and health, some annuities), describing the loss exposures and bases and methodologies for making the relevant accounting estimates. |
| cm:Level2TextBlock |
| Text Block (HTML) (nonnum:textBlockItemType) |
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| us-gaap:ContingentLiabilityReserveEstimatePolicy |