| Standard label: | Interest Income, Securities, Operating, Tax Exempt |
| Name: | us-gaap:InterestIncomeSecuritiesTaxExempt |
| Documentation: | Amount of operating interest income, including amortization and accretion of premiums and discounts, on securities exempt from state, federal and other income tax. |
| Object type: | cm:Concept |
| Data type: | Monetary (xbrli:monetaryItemType) |
| Period type: | For Period (duration) |
| Balance type: | Credit |
| Abstract: | false |
| Workiva Wdesk Taxonomy Analyzer: | us-gaap:InterestIncomeSecuritiesTaxExempt |
| Label | Role | Language |
| Interest Income, Securities, Operating, Tax Exempt | http://www.xbrl.org/2003/role/label | en-US |
| Reference | Role | Topic |
| FASB Accounting Standards Codification 942 220 S99 1 (SX 210.9-04.2) | http://fasb.org/us-gaap/role/ref/legacyRef | 942 |
| Part Of Roll Up: |
| us-gaap:InterestIncomeOperating |