cm:Concept: us-gaap:ClosedBlockOperationsChangeInPolicyholderBenefitsAndInterestCreditedToPolicyholderAccountBalances
| Closed Block Operations, Change in Policyholder Benefits and Interest Credited to Policyholder Account Balances |
| us-gaap:ClosedBlockOperationsChangeInPolicyholderBenefitsAndInterestCreditedToPolicyholderAccountBalances |
| Difference between prior period and current period estimated policy claims and interest due to and designated to policies in an insurance entity's segregated group of participating or dividend-paying policies and contracts along with the assets allocated to them (known as a closed block). |
| cm:Concept |
| Monetary (xbrli:monetaryItemType) |
| For Period (duration) |
| Debit |
| false |
| us-gaap:ClosedBlockOperationsChangeInPolicyholderBenefitsAndInterestCreditedToPolicyholderAccountBalances |