| Standard label: | Debt Securities, Available-for-sale, Unrealized Loss Position |
| Name: | us-gaap:DebtSecuritiesAvailableForSaleUnrealizedLossPosition |
| Documentation: | Amount of investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale), in unrealized loss position without allowance for credit loss. |
| Object type: | cm:Concept |
| Data type: | Monetary (xbrli:monetaryItemType) |
| Period type: | As Of (instant) |
| Balance type: | Debit |
| Abstract: | false |
| Workiva Wdesk Taxonomy Analyzer: | us-gaap:DebtSecuritiesAvailableForSaleUnrealizedLossPosition |
| Label | Role | Language |
| Debt Securities, Available-for-sale, Unrealized Loss Position | http://www.xbrl.org/2003/role/label | en-US |
| Debt Securities, Available-for-sale, Unrealized Loss Position, Total | http://www.xbrl.org/2003/role/totalLabel | en-US |
| Reference | Role | Topic |
| FASB Accounting Standards Codification 320 10 50 6 (a)(1) | http://www.xbrl.org/2003/role/disclosureRef | 320 |
| FASB Accounting Standards Codification 326 30 50 4 (a)(1) | http://www.xbrl.org/2003/role/disclosureRef | 326 |
| FASB Accounting Standards Codification 326 30 55 8 | http://www.xbrl.org/2003/role/exampleRef | 326 |