| Standard label: | Liability for Catastrophe Claims Disclosure [Table Text Block] |
| Name: | us-gaap:LiabilityForCatastropheClaimsDisclosureTextBlock |
| Documentation: | Tabular disclosure of the risk of loss equal to the estimated amount of payments on costs of settling insured claims and costs incurred in the claims settlement process and future benefit payments resulting from conflagration, earthquake, windstorm, explosion, or similar event resulting in substantial losses that have occurred as of the balance sheet date, identified by business segment and country. |
| Object type: | cm:Level3TextBlock |
| Data type: | Text Block (HTML) (nonnum:textBlockItemType) |
| Period type: | For Period (duration) |
| Balance type: | (no balance type) |
| Abstract: | false |
| Workiva Wdesk Taxonomy Analyzer: | us-gaap:LiabilityForCatastropheClaimsDisclosureTextBlock |
| Label | Role | Language |
| Liability for Catastrophe Claims Disclosure [Table Text Block] | 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 |