| Standard label: | Gain (Loss) on Sales of Loans, Net |
| Name: | us-gaap:GainLossOnSalesOfLoansNet |
| Documentation: | The net gain (loss) resulting from a sale of loans, including adjustments to record loans classified as held-for-sale at the lower-of-cost-or-market and fair value adjustments to loan held for investment purposes. |
| 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:GainLossOnSalesOfLoansNet |
| Label | Role | Language |
| Gain (Loss) on Sales of Loans, Net | http://www.xbrl.org/2003/role/label | en-US |
| Gain (Loss) on Sales of Loans, Net, Total | http://www.xbrl.org/2003/role/totalLabel | en-US |
| Reference | Role | Topic |
| FASB Accounting Standards Codification 230 10 45 28 (b) | http://fasb.org/us-gaap/role/ref/legacyRef | 230 |
| FASB Accounting Standards Codification 942 220 S99 1 (SX 210.9-04.13(h)) | http://fasb.org/us-gaap/role/ref/legacyRef | 942 |
| FASB Accounting Standards Codification 944 220 S99 1 (SX 210.7-04.3(a)) | http://fasb.org/us-gaap/role/ref/legacyRef | 944 |
| Part Of Roll Up: |
| us-gaap:GainsLossesOnSalesOfAssets |
| us-gaap:GainLossOnSaleOfLoansAndLeases |