cm:Concept: us-gaap:MarketRiskBenefitReinsuranceRecoverableAfterAllowance
| Market Risk Benefit, Reinsurance Recoverable, after Allowance |
| us-gaap:MarketRiskBenefitReinsuranceRecoverableAfterAllowance |
| Amount, after allowance for credit loss, recoverable under reinsurance for contract or contract feature in long-duration contract issued by insurance entity that both protects contract holder from other-than-nominal capital market risk and exposes insurance entity to other-than-nominal capital market risk. |
| cm:Concept |
| Monetary (xbrli:monetaryItemType) |
| As Of (instant) |
| Debit |
| false |
| us-gaap:MarketRiskBenefitReinsuranceRecoverableAfterAllowance |