cm:Concept: us-gaap:ClosedBlockInvestmentsFixedMaturityAvailableForSaleAmortizedCost
| Closed Block Investments, Fixed Maturity, Available-for-sale, Amortized Cost |
| us-gaap:ClosedBlockInvestmentsFixedMaturityAvailableForSaleAmortizedCost |
| The amortized cost as of the balance sheet date of those fixed maturity investments designated as available for sale and reported at fair value which are allocated to the closed block. Also a component of change in other comprehensive income in the period, which is reflected in the closed block disclosure. |
| cm:Concept |
| Monetary (xbrli:monetaryItemType) |
| As Of (instant) |
| Debit |
| false |
| us-gaap:ClosedBlockInvestmentsFixedMaturityAvailableForSaleAmortizedCost |