| Standard label: | Other Comprehensive Income (Loss), Available-for-sale Securities Adjustment, Net of Tax, Portion Attributable to Parent |
| Name: | us-gaap:OtherComprehensiveIncomeAvailableforsaleSecuritiesAdjustmentNetOfTaxPortionAttributableToParent |
| Documentation: | Amount after tax and reclassification adjustments, of appreciation (loss) in value of unsold available-for-sale securities, attributable to parent entity. Excludes amounts related to other than temporary impairment (OTTI) loss. |
| 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:OtherComprehensiveIncomeAvailableforsaleSecuritiesAdjustmentNetOfTaxPortionAttributableToParent |
| Label | Role | Language |
| Other Comprehensive Income (Loss), Available-for-sale Securities Adjustment, Net of Tax, Portion Attributable to Parent | http://www.xbrl.org/2003/role/label | en-US |
| Other Comprehensive Income (Loss), Available-for-sale Securities Adjustment, Net of Tax, Portion Attributable to Parent, Total | http://www.xbrl.org/2003/role/totalLabel | en-US |
| Reference | Role | Topic |
| FASB Accounting Standards Codification 810 10 50 1A (c)(3) | http://fasb.org/us-gaap/role/ref/legacyRef | 810 |
| FASB Accounting Standards Codification 810 10 45 19 | http://fasb.org/us-gaap/role/ref/legacyRef | 810 |
| FASB Accounting Standards Codification 810 10 45 20 | http://fasb.org/us-gaap/role/ref/legacyRef | 810 |