cm:Member: us-gaap:ReturnOfNetDepositsAccruedAtStatedRateMember
| Return of Net Deposits Accrued at Stated Rate [Member] |
| us-gaap:ReturnOfNetDepositsAccruedAtStatedRateMember |
| Guarantee for a return of net deposit plus an accrual at a stated interest rate on a guaranteed benefit obligation in traditional and nontraditional long-duration contracts with policy and contract holders. |
| cm:Member |
| [Member] (nonnum:domainItemType) |
| For Period (duration) |
| (no balance type) |
| true |
| us-gaap:ReturnOfNetDepositsAccruedAtStatedRateMember |