| Standard label: | Increase (Decrease) in Deposit Assets |
| Name: | us-gaap:IncreaseDecreaseInDepositOtherAssets |
| Documentation: | The increase (decrease) during the reporting period in moneys or securities given as security including, but not limited to, contract, escrow, or earnest money deposits, retainage (if applicable), deposits with clearing organizations and others, collateral, or margin deposits. |
| 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:IncreaseDecreaseInDepositOtherAssets |
| Label | Role | Language |
| Increase (Decrease) in Deposit Assets | http://www.xbrl.org/2003/role/label | en-US |
| Increase (Decrease) in Deposit Assets, Total | http://www.xbrl.org/2003/role/totalLabel | en-US |
| Reference | Role | Topic |
| FASB Accounting Standards Codification 230 10 45 28 (a) | http://fasb.org/us-gaap/role/ref/legacyRef | 230 |
| Part Of Roll Up: |
| us-gaap:IncreaseDecreaseInOperatingAssets |