cm:Concept: us-gaap:OciLiabilityForFuturePolicyBenefitGainLossAfterReclassificationAdjustmentAndTaxNoncontrollingInterest
| OCI, Liability for Future Policy Benefit, Gain (Loss), after Reclassification Adjustment and Tax, Noncontrolling Interest |
| us-gaap:OciLiabilityForFuturePolicyBenefitGainLossAfterReclassificationAdjustmentAndTaxNoncontrollingInterest |
| Amount, after tax and reclassification adjustment, of unrealized gain (loss) from (increase) decrease in liability for future policy benefit from change in discount rate, attributable to noncontrolling interest. |
| cm:Concept |
| Monetary (xbrli:monetaryItemType) |
| For Period (duration) |
| Debit |
| false |
| us-gaap:OciLiabilityForFuturePolicyBenefitGainLossAfterReclassificationAdjustmentAndTaxNoncontrollingInterest |