| Standard label: | Available-for-sale Equity Securities, Gross Unrealized Loss |
| Name: | us-gaap:AvailableForSaleEquitySecuritiesGrossUnrealizedLoss |
| Documentation: | Amount of unrealized loss before deducting unrealized gain on investments in available-for-sale equity securities. |
| 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:AvailableForSaleEquitySecuritiesGrossUnrealizedLoss |
| Label | Role | Language |
| Available-for-sale Equity Securities, Gross Unrealized Loss | http://www.xbrl.org/2003/role/label | en-US |
| Reference | Role | Topic |
| FASB Accounting Standards Codification 320 10 50 2 (c) | http://fasb.org/us-gaap/role/ref/legacyRef | 320 |