cm:Concept: us-gaap:ShortdurationInsuranceContractsIncurredClaimsAndAllocatedClaimAdjustmentExpenseNet
| Short-duration Insurance Contracts, Incurred Claims and Allocated Claim Adjustment Expense, Net |
| us-gaap:ShortdurationInsuranceContractsIncurredClaimsAndAllocatedClaimAdjustmentExpenseNet |
| Undiscounted amount, after reinsurance, of incurred claims and allocated claim adjustment expense used in claims development for short-duration insurance contracts. Excludes unallocated claim adjustment expense. |
| cm:Concept |
| Monetary (xbrli:monetaryItemType) |
| As Of (instant) |
| Credit |
| false |
| us-gaap:ShortdurationInsuranceContractsIncurredClaimsAndAllocatedClaimAdjustmentExpenseNet |