| Standard label: | Debt Securities, Held-to-maturity, Allowance for Credit Loss |
| Name: | us-gaap:DebtSecuritiesHeldToMaturityAllowanceForCreditLoss |
| Documentation: | Amount of allowance for credit loss for debt security measured at amortized cost (held-to-maturity). |
| Object type: | cm:Concept |
| Data type: | Monetary (xbrli:monetaryItemType) |
| Period type: | As Of (instant) |
| Balance type: | Credit |
| Abstract: | false |
| Workiva Wdesk Taxonomy Analyzer: | us-gaap:DebtSecuritiesHeldToMaturityAllowanceForCreditLoss |
| Label | Role | Language |
| Debt Securities, Held-to-maturity, Allowance for Credit Loss | http://www.xbrl.org/2003/role/label | en-US |
| Debt Securities, Held-to-maturity, Allowance for Credit Loss, Ending Balance | http://www.xbrl.org/2003/role/periodEndLabel | en-US |
| Debt Securities, Held-to-maturity, Allowance for Credit Loss, Beginning Balance | http://www.xbrl.org/2003/role/periodStartLabel | en-US |
| Debt Securities, Held-to-maturity, Allowance for Credit Loss, Total | http://www.xbrl.org/2003/role/totalLabel | en-US |
| Reference | Role | Topic |
| FASB Accounting Standards Codification 320 10 50 5 (aaa) | http://www.xbrl.org/2003/role/disclosureRef | 320 |
| FASB Accounting Standards Codification 326 20 45 1 | http://www.xbrl.org/2003/role/disclosureRef | 326 |
| FASB Accounting Standards Codification 326 20 50 13 (a) | http://www.xbrl.org/2003/role/disclosureRef | 326 |
| FASB Accounting Standards Codification 326 20 50 13 (f) | http://www.xbrl.org/2003/role/disclosureRef | 326 |