| Standard label: | Liability for Catastrophe Claims, Carrying Amount |
| Name: | us-gaap:LiabilityForCatastropheClaimsCarryingAmount |
| Documentation: | The amount of estimated liability as of the balance sheet date for the specific conflagration, earthquake, windstorm, explosion, or similar event. |
| Object type: | cm:Concept |
| Data type: | Monetary (xbrli:monetaryItemType) |
| Period type: | As Of (instant) |
| Balance type: | Credit |
| Abstract: | false |
| Workiva Wdesk Taxonomy Analyzer: | us-gaap:LiabilityForCatastropheClaimsCarryingAmount |
| Label | Role | Language |
| Liability for Catastrophe Claims, Carrying Amount | http://www.xbrl.org/2003/role/label | en-US |
| Reference | Role | Topic |
| FASB Accounting Standards Codification 944 40 50 3 | http://fasb.org/us-gaap/role/ref/legacyRef | 944 |