| Standard label: | Standby Letters of Credit [Member] |
| Name: | us-gaap:StandbyLettersOfCreditMember |
| Documentation: | An irrevocable undertaking (typically by a financial institution) to guarantee payment of a specified financial obligation. |
| Object type: | cm:Member |
| Data type: | [Member] (nonnum:domainItemType) |
| Period type: | For Period (duration) |
| Balance type: | (no balance type) |
| Abstract: | true |
| Workiva Wdesk Taxonomy Analyzer: | us-gaap:StandbyLettersOfCreditMember |
| Label | Role | Language |
| Standby Letters of Credit [Member] | http://www.xbrl.org/2003/role/label | en-US |
| Reference | Role | Topic |
| FASB Accounting Standards Codification 460 10 55 2 (a) | http://fasb.org/us-gaap/role/ref/legacyRef | 460 |
| FASB Accounting Standards Codification 460 10 50 2 (b) | http://www.xbrl.org/2003/role/disclosureRef | 460 |
| FASB Accounting Standards Codification 810 10 15 12 (f)(2) | http://fasb.org/us-gaap/role/ref/legacyRef | 810 |
| FASB Accounting Standards Codification 946 20 50 15 (a) | http://fasb.org/us-gaap/role/ref/legacyRef | 946 |