cm:Concept: us-gaap:LiabilityForFuturePolicyBenefitsIndividualAndGroupAnnuitiesAndSupplementaryContracts
| Liability for Future Policy Benefits, Individual and Group Annuities and Supplementary Contracts |
| us-gaap:LiabilityForFuturePolicyBenefitsIndividualAndGroupAnnuitiesAndSupplementaryContracts |
| Amount of accrued obligation to policyholders that relates to insured events under individual and group annuities and supplementary insurance contracts. |
| cm:Concept |
| Monetary (xbrli:monetaryItemType) |
| As Of (instant) |
| Credit |
| false |
| us-gaap:LiabilityForFuturePolicyBenefitsIndividualAndGroupAnnuitiesAndSupplementaryContracts |