| Standard label: | Environmental Exit Costs by Cost [Table Text Block] | 
| Name: | us-gaap:EnvironmentalExitCostsByCostTextBlock | 
| Documentation: | Tabular disclosure of material liabilities for remediation, site restoration, postclosure, monitoring commitments, or other exit costs that may occur on the sale, disposal or abandonment of a property as a result of unanticipated contamination of the assets. | 
| 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:EnvironmentalExitCostsByCostTextBlock | 
| Examples of this text block disclosure: | EnvironmentalExitCost | 
| Label | Role | Language | 
| Environmental Exit Costs by Cost [Table Text Block] | http://www.xbrl.org/2003/role/label | en-US | 
| Reference | Role | Topic | 
| FASB Accounting Standards Codification 450 20 S99 1 (SAB Topic 5.Y.Q4) | http://fasb.org/us-gaap/role/ref/legacyRef | 450 |