| Standard label: | Debt Securities, Held-to-maturity, Change in Present Value, Expense (Reversal) |
| Name: | us-gaap:DebtSecuritiesHeldToMaturityChangeInPresentValueExpenseReversal |
| Documentation: | Amount of expense (reversal of expense) for expected credit loss on investment in debt security measured at amortized cost (held-to-maturity), from change in present value of expected cash flows. |
| 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:DebtSecuritiesHeldToMaturityChangeInPresentValueExpenseReversal |
| Label | Role | Language |
| Debt Securities, Held-to-maturity, Change in Present Value, Expense (Reversal) | http://www.xbrl.org/2003/role/label | en-US |
| Reference | Role | Topic |
| FASB Accounting Standards Codification 326 20 45 3 | http://www.xbrl.org/2003/role/disclosureRef | 326 |
| FASB Accounting Standards Codification 326 20 50 12 | http://www.xbrl.org/2003/role/disclosureRef | 326 |