| Standard label: | Other Comprehensive (Income) Loss, Reclassification Adjustment from AOCI for Write-down of Securities, Tax |
| Name: | us-gaap:OtherComprehensiveIncomeLossReclassificationAdjustmentFromAOCIForWritedownOfSecuritiesTax |
| Documentation: | Amount of tax (expense) benefit of reclassification adjustment from accumulated other comprehensive income for unrealized loss realized upon the write-down of available-for-sale securities. |
| Object type: | cm:Concept |
| Data type: | Monetary (xbrli:monetaryItemType) |
| Period type: | For Period (duration) |
| Balance type: | Debit |
| Abstract: | false |
| Workiva Wdesk Taxonomy Analyzer: | us-gaap:OtherComprehensiveIncomeLossReclassificationAdjustmentFromAOCIForWritedownOfSecuritiesTax |
| Label | Role | Language |
| Other Comprehensive (Income) Loss, Reclassification Adjustment from AOCI for Write-down of Securities, Tax | http://www.xbrl.org/2003/role/label | en-US |
| Other Comprehensive (Income) Loss, Reclassification Adjustment from AOCI for Write-down of Securities, Tax, Total | http://www.xbrl.org/2003/role/totalLabel | en-US |
| Reference | Role | Topic |
| FASB Accounting Standards Codification 220 10 45 12 | http://fasb.org/us-gaap/role/ref/legacyRef | 220 |