| Standard label: | Loss from Catastrophes | 
| Name: | us-gaap:LossFromCatastrophes | 
| Documentation: | The charge against earnings in the period for the uninsured portion of a loss from a fire, explosion, or natural disaster (hurricane, earthquake). | 
| Object type: | cm:Concept | 
| Data type: | Monetary (xbrli:monetaryItemType) | 
| Period type: | For Period (duration) | 
| Balance type: | Debit | 
| Abstract: | false | 
| Workiva Wdesk Taxonomy Analyzer: | us-gaap:LossFromCatastrophes | 
| Label | Role | Language | 
| Loss from Catastrophes | http://www.xbrl.org/2003/role/label | en-US | 
| Reference | Role | Topic | 
| FASB Accounting Standards Codification 220 10 S99 2 (SX 210.5-03.9) | http://fasb.org/us-gaap/role/ref/legacyRef | 220 | 
| Part Of Roll Up: | 
| us-gaap:NonoperatingIncomeExpense |