| Standard label: | Debt Securities, Available-for-sale, Allowance for Credit Loss, Securities Sold |
| Name: | us-gaap:DebtSecuritiesAvailableForSaleAllowanceForCreditLossSecuritiesSold |
| Documentation: | Amount of decrease in allowance for credit loss on investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale) from sale. |
| 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:DebtSecuritiesAvailableForSaleAllowanceForCreditLossSecuritiesSold |
| Label | Role | Language |
| Debt Securities, Available-for-sale, Allowance for Credit Loss, Securities Sold | http://www.xbrl.org/2003/role/label | en-US |
| Reference | Role | Topic |
| FASB Accounting Standards Codification 326 30 50 9 (d) | http://www.xbrl.org/2003/role/disclosureRef | 326 |