| Standard label: | Other Comprehensive Loss, Held-to-maturity Security, OTTI, after Tax and Adjustments |
| Name: | us-gaap:OtherComprehensiveLossHeldToMaturitySecurityOttiAfterTaxAndAdjustments |
| Documentation: | Amount, after tax and adjustments, of increase (decrease) in other than temporary impairment (OTTI) on investment in held-to-maturity security, recognized in other comprehensive loss. |
| Object type: | cm:Concept |
| Data type: | Monetary (xbrli:monetaryItemType) |
| Period type: | For Period (duration) |
| Balance type: | Debit |
| Abstract: | false |
| Workiva Wdesk Taxonomy Analyzer: | us-gaap:OtherComprehensiveLossHeldToMaturitySecurityOttiAfterTaxAndAdjustments |
| Label | Role | Language |
| Other Comprehensive Loss, Held-to-maturity Security, OTTI, after Tax and Adjustments | http://www.xbrl.org/2003/role/label | en-US |
| Other Comprehensive Loss, Held-to-maturity Security, OTTI, after Tax and Adjustments, Total | http://www.xbrl.org/2003/role/totalLabel | en-US |
| Reference | Role | Topic |
| FASB Accounting Standards Codification 220 10 45 16A | http://fasb.org/us-gaap/role/ref/legacyRef | 220 |
| FASB Accounting Standards Codification 220 10 45 10A (g) | http://fasb.org/us-gaap/role/ref/legacyRef | 220 |
| FASB Accounting Standards Codification 320 10 35 35A | http://fasb.org/us-gaap/role/ref/legacyRef | 320 |
| 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 |