| Standard label: | Securities Owned and Other Investments Not Readily Marketable Disclosure [Table Text Block] |
| Name: | us-gaap:SecuritiesOwnedAndOtherInvestmentsNotReadilyMarketableDisclosureTextBlock |
| Documentation: | Tabular disclosure of quantitative and qualitative information related to securities and other investments not readily marketable, including, but not limited to, thinly traded securities or investments, restricted securities and securities in nonpublic entities. |
| 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:SecuritiesOwnedAndOtherInvestmentsNotReadilyMarketableDisclosureTextBlock |
| Label | Role | Language |
| Securities Owned and Other Investments Not Readily Marketable Disclosure [Table Text Block] | http://www.xbrl.org/2003/role/label | en-US |
| Reference | Role | Topic |
| FASB Accounting Standards Codification 940 820 50 1 | http://fasb.org/us-gaap/role/ref/legacyRef | 940 |