| Standard label: | Trading Gain (Loss) |
| Name: | us-gaap:TradingGainsLosses |
| Documentation: | Amount of gain (loss) resulting from the difference between the acquisition price and the selling price or fair value of trading assets and trading liabilities, conducted separately from customer trading activities. Includes, but is not limited to, changes in fair value of trading assets and trading liabilities. |
| 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:TradingGainsLosses |
| Label | Role | Language |
| Trading Gain (Loss) | http://www.xbrl.org/2003/role/label | en-US |
| Trading Gain (Loss), Total | http://www.xbrl.org/2003/role/totalLabel | en-US |
| Reference | Role | Topic |
| FASB Accounting Standards Codification 815 10 50 4F (a) | http://fasb.org/us-gaap/role/ref/legacyRef | 815 |
| FASB Accounting Standards Codification 940 320 35 3 | http://fasb.org/us-gaap/role/ref/legacyRef | 940 |
| FASB Accounting Standards Codification 940 320 45 5 | http://fasb.org/us-gaap/role/ref/legacyRef | 940 |
| FASB Accounting Standards Codification 942 220 S99 1 (SX 210.9-04.13(e)) | http://fasb.org/us-gaap/role/ref/legacyRef | 942 |
| Part Of Roll Up: |
| us-gaap:PrincipalTransactionsRevenue |