cm:Concept: us-gaap:AssumedLiabilityForUnpaidClaimsAndClaimsAdjustmentExpense
| Assumed Liability for Unpaid Claims and Claims Adjustment Expense |
| us-gaap:AssumedLiabilityForUnpaidClaimsAndClaimsAdjustmentExpense |
| Liability as of the balance sheet date for the estimated ultimate cost of settling claims and claim adjustment expense relating to insured events that have occurred on or before the balance sheet date for those liabilities owed to another party as a result of assuming another insurer's primary obligation. |
| cm:Concept |
| Monetary (xbrli:monetaryItemType) |
| As Of (instant) |
| Credit |
| false |
| us-gaap:AssumedLiabilityForUnpaidClaimsAndClaimsAdjustmentExpense |