| Standard label: | Schedule of Repurchase Agreement Counterparties with Whom Repurchase Agreements Exceed 10 Percent of Stockholders' Equity [Table Text Block] |
| Name: | us-gaap:ScheduleOfRepurchaseAgreementCounterpartiesWithWhomRepurchaseAgreementsExceed10PercentOfStockholdersEquityTextBlock |
| Documentation: | Tabular disclosure, as of the balance sheet date, of the amount at risk under repurchase agreements with any individual counterparty or group of related counterparties which exceeds 10 percent of stockholders' equity. Includes the name of each counterparty or group of related counterparties, the amount at risk with each, and the weighted average maturity of the repurchase agreements with each. The amount at risk under repurchase agreements is defined as the excess of carrying amount (or market value, if higher than the carrying amount or if there is no carrying amount) of the securities or other assets sold under agreement to repurchase, including accrued interest plus any cash or other assets on deposit to secure the repurchase obligation, over the amount of the repurchase liability (adjusted for accrued interest). |
| 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:ScheduleOfRepurchaseAgreementCounterpartiesWithWhomRepurchaseAgreementsExceed10PercentOfStockholdersEquityTextBlock |
| Label | Role | Language |
| Schedule of Repurchase Agreement Counterparties with Whom Repurchase Agreements Exceed 10 Percent of Stockholders' Equity [Table 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)(1)(i)(B)(iii)) | http://fasb.org/us-gaap/role/ref/legacyRef | 235 |