cm:Member: us-gaap:AociMarketRiskBenefitInstrumentSpecificCreditRiskNoncontrollingInterestMember
| AOCI, Market Risk Benefit, Instrument-Specific Credit Risk, Noncontrolling Interest [Member] |
| us-gaap:AociMarketRiskBenefitInstrumentSpecificCreditRiskNoncontrollingInterestMember |
| Accumulated other comprehensive income (loss) (AOCI) from (increase) decrease in instrument-specific credit risk on contract or contract feature in long-duration contract issued by insurance entity protecting contract holder from other-than-nominal capital market risk and exposing insurance entity to other-than-nominal capital market risk, attributable to noncontrolling interest. |
| cm:Member |
| [Member] (nonnum:domainItemType) |
| For Period (duration) |
| (no balance type) |
| true |
| us-gaap:AociMarketRiskBenefitInstrumentSpecificCreditRiskNoncontrollingInterestMember |