cm:Concept: us-gaap:ClosedBlockAssetsAndLiabilitiesChangeInPolicyholderDividendObligation
| Closed Block Assets and Liabilities, Change in Policyholder Dividend Obligation |
| us-gaap:ClosedBlockAssetsAndLiabilitiesChangeInPolicyholderDividendObligation |
| For the segregated group of participating or dividend-paying policies and contracts identified as the closed block, the change in the period in the obligation representing amounts to be distributed to policyholders owning contracts in 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) |
| Credit |
| false |
| us-gaap:ClosedBlockAssetsAndLiabilitiesChangeInPolicyholderDividendObligation |