cm:Concept: us-gaap:AssetsDesignatedToClosedBlockMortgageLoansOnRealEstate
| Assets Designated to Closed Block, Mortgage Loans on Real Estate |
| us-gaap:AssetsDesignatedToClosedBlockMortgageLoansOnRealEstate |
| Carrying amount of investments in mortgage loans on real estate allocated to the segregated group of participating or dividend-paying policies and contracts identified as the closed block. |
| cm:Concept |
| Monetary (xbrli:monetaryItemType) |
| As Of (instant) |
| Debit |
| false |
| us-gaap:AssetsDesignatedToClosedBlockMortgageLoansOnRealEstate |