cm:Table: us-gaap:ShortdurationInsuranceContractsReconciliationOfClaimsDevelopmentToLiabilityTable
| Short-duration Insurance Contracts, Reconciliation of Claims Development to Liability [Table] |
| us-gaap:ShortdurationInsuranceContractsReconciliationOfClaimsDevelopmentToLiabilityTable |
| Disclosure of information about the reconciliation of claims development to the liability for unpaid claims and claim adjustment expense for short-duration insurance contracts. |
| cm:Table |
| Text/String (xbrli:stringItemType) |
| For Period (duration) |
| (no balance type) |
| true |
| us-gaap:ShortdurationInsuranceContractsReconciliationOfClaimsDevelopmentToLiabilityTable |