| Standard label: | Securities Borrowed and Loaned Policy [Policy Text Block] |
| Name: | us-gaap:SecuritiesBorrowedAndLoanedPolicy |
| Documentation: | Disclosure of accounting policy for securities borrowed or loaned by the entity. Disclosure may include a description of the business purposes for the transactions, how the transactions are recognized in the financial statements, the types of securities involved in the transactions, the method for monitoring the market value of the securities, the entity's practice and policies associated with cash deposits and collateral for the transactions, and the classification of fees and interest associated with the transactions. |
| Object type: | cm:Level2TextBlock |
| 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:SecuritiesBorrowedAndLoanedPolicy |
| Label | Role | Language |
| Securities Borrowed and Loaned Policy [Policy Text Block] | http://www.xbrl.org/2003/role/label | en-US |
| Reference | Role | Topic |
| FASB Accounting Standards Codification 235 10 S99 1 (SX 210.4-08.(m)(2)(i)) | http://fasb.org/us-gaap/role/ref/legacyRef | 235 |
| FASB Accounting Standards Codification 235 10 50 3 | http://fasb.org/us-gaap/role/ref/legacyRef | 235 |
| FASB Accounting Standards Codification 860 30 50 1A (a) | http://fasb.org/us-gaap/role/ref/legacyRef | 860 |