cm:Concept: us-gaap:ProceedsFromIssuanceOfTrustPreferredSecurities
| Proceeds from Issuance of Trust Preferred Securities |
| us-gaap:ProceedsFromIssuanceOfTrustPreferredSecurities |
| The cash inflow from issuance of preferred stocks by a business trust or other special purpose entity, mainly established by a bank holding entity, to third party investors. The trust's assets are deeply subordinated debentures of the bank holding entity. Most trust preferred securities are subject to a mandatory redemption upon the repayment of the debentures. |
| cm:Concept |
| Monetary (xbrli:monetaryItemType) |
| For Period (duration) |
| Debit |
| false |
| us-gaap:ProceedsFromIssuanceOfTrustPreferredSecurities |