cm:Concept: us-gaap:LiabilitiesForGuaranteesOnLongDurationContractsIncurredBenefits1
| Liabilities for Guarantees on Long-Duration Contracts, Incurred Benefits |
| us-gaap:LiabilitiesForGuaranteesOnLongDurationContractsIncurredBenefits1 |
| Amount of guaranteed minimum benefit expense incurred for expected guaranteed minimum benefits in excess of projected account values. |
| cm:Concept |
| Monetary (xbrli:monetaryItemType) |
| For Period (duration) |
| Debit |
| false |
| us-gaap:LiabilitiesForGuaranteesOnLongDurationContractsIncurredBenefits1 |