cm:Table: us-gaap:ShortdurationInsuranceContractsHistoricalClaimsDurationTable
| Short-duration Insurance Contracts, Historical Claims Duration [Table] |
| us-gaap:ShortdurationInsuranceContractsHistoricalClaimsDurationTable |
| Disclosure of information about average annual percentage payout of incurred claims by age, after reinsurance, for short-duration insurance contracts. |
| cm:Table |
| Text/String (xbrli:stringItemType) |
| For Period (duration) |
| (no balance type) |
| true |
| us-gaap:ShortdurationInsuranceContractsHistoricalClaimsDurationTable |