| Standard label: | Gain (Loss) on Sale of Investments |
| Name: | us-gaap:GainLossOnSaleOfInvestments |
| Documentation: | The net realized gain (loss) on investments sold during the period, not including gains (losses) on securities separately or otherwise categorized as trading, available-for-sale, or held-to-maturity, which, for cash flow reporting, is a component of proceeds from investing activities. |
| 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:GainLossOnSaleOfInvestments |
| Label | Role | Language |
| Gain (Loss) on Sale of Investments | http://www.xbrl.org/2003/role/label | en-US |
| Gain (Loss) on Sale of Investments, 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 |