cm:Level3TextBlock: us-gaap:MarketRiskBenefitActivityTableTextBlock
| Market Risk Benefit, Activity [Table Text Block] |
| us-gaap:MarketRiskBenefitActivityTableTextBlock |
| Tabular disclosure of beginning balance to ending balance 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:Level3TextBlock |
| Text Block (HTML) (nonnum:textBlockItemType) |
| For Period (duration) |
| (no balance type) |
| false |
| us-gaap:MarketRiskBenefitActivityTableTextBlock |