cm:Concept: us-gaap:ClosedBlockOperationsPremiums
| Closed Block Operations, Premiums |
| us-gaap:ClosedBlockOperationsPremiums |
| For the segregated group of participating or dividend-paying policies and contracts along with the assets allocated to them (known as a closed block), revenue for the period from insurance policy premiums; typically included in a table of closed block operations. |
| cm:Concept |
| Monetary (xbrli:monetaryItemType) |
| For Period (duration) |
| Credit |
| false |
| us-gaap:ClosedBlockOperationsPremiums |