| Standard label: | Variable Interest Entity Disclosure [Text Block] |
| Name: | us-gaap:VariableInterestEntityDisclosureTextBlock |
| Documentation: | The entire disclosure for a variable interest entity (VIE), including but not limited to, judgments and assumptions in determining whether to consolidate and in identifying the primary beneficiary, gain (loss) recognized on the initial consolidation of the VIE, terms of arrangements, amounts and classification of the VIE's assets and liabilities, and the entity's maximum exposure to loss. |
| 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:VariableInterestEntityDisclosureTextBlock |
| Label | Role | Language |
| Variable Interest Entity Disclosure [Text Block] | http://www.xbrl.org/2003/role/label | en-US |
| Reference | Role | Topic |
| FASB Accounting Standards Codification 810 | http://fasb.org/us-gaap/role/ref/legacyRef | 810 |