cm:Table: us-gaap:NetAmountAtRiskByProductAndGuaranteeTable
| Net Amount at Risk, by Product and Guarantee [Table] |
| us-gaap:NetAmountAtRiskByProductAndGuaranteeTable |
| For contracts with guaranteed benefits in excess of the current account balance, sets forth the amounts of such excesses (the net amounts at risk) and other pertinent information by type of guarantee by type of insurance product), as of the most recent balance sheet date. |
| cm:Table |
| Text/String (xbrli:stringItemType) |
| For Period (duration) |
| (no balance type) |
| true |
| us-gaap:NetAmountAtRiskByProductAndGuaranteeTable |