| Standard label: | Residential Mortgage Backed Securities [Member] |
| Name: | us-gaap:ResidentialMortgageBackedSecuritiesMember |
| Documentation: | Securities collateralized by residential real estate mortgage loans. |
| 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:ResidentialMortgageBackedSecuritiesMember |
| Label | Role | Language |
| Residential Mortgage Backed Securities [Member] | http://www.xbrl.org/2003/role/label | en-US |
| Reference | Role | Topic |
| FASB Accounting Standards Codification 320 10 50 1B | http://www.xbrl.org/2009/role/commonPracticeRef | 320 |
| FASB Accounting Standards Codification 715 20 50 1 (d)(ii) | http://www.xbrl.org/2009/role/commonPracticeRef | 715 |