| Standard label: | Investment [Text Block] |
| Name: | us-gaap:InvestmentTextBlock |
| Documentation: | The entire disclosure for investment. |
| Object type: | cm:Level1TextBlock |
| 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:InvestmentTextBlock |
| Label | Role | Language |
| Investment [Text Block] | http://www.xbrl.org/2003/role/label | en-US |
| Reference | Role | Topic |
| FASB Accounting Standards Codification 320 | http://www.xbrl.org/2009/role/commonPracticeRef | 320 |
| FASB Accounting Standards Codification 321 | http://www.xbrl.org/2009/role/commonPracticeRef | 321 |
| FASB Accounting Standards Codification 323 | http://www.xbrl.org/2009/role/commonPracticeRef | 323 |
| FASB Accounting Standards Codification 325 | http://www.xbrl.org/2009/role/commonPracticeRef | 325 |