| Standard label: | Deposit Assets, Amortizaton Expense from Expirations |
| Name: | us-gaap:DepositAssetsAmortizatonExpenseFromExpirations |
| Documentation: | Amount of amortization expense from expiration of contracts underlying deposit assets. |
| 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:DepositAssetsAmortizatonExpenseFromExpirations |
| Label | Role | Language |
| Deposit Assets, Amortizaton Expense from Expirations | http://www.xbrl.org/2003/role/label | en-US |
| Reference | Role | Topic |
| FASB Accounting Standards Codification 340 30 50 2 (c) | http://fasb.org/us-gaap/role/ref/legacyRef | 340 |