| Standard label: | Gain (Loss) on Investments |
| Name: | us-gaap:GainLossOnInvestments |
| Documentation: | Amount of realized and unrealized gain (loss) on investment. |
| 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:GainLossOnInvestments |
| Label | Role | Language |
| Gain (Loss) on Investments | http://www.xbrl.org/2003/role/label | en-US |
| Gain (Loss) on Investments, Total | http://www.xbrl.org/2003/role/totalLabel | en-US |
| Reference | Role | Topic |
| FASB Accounting Standards Codification 220 10 S99 2 (SX 210.5-03.7(c),9(a)) | http://fasb.org/us-gaap/role/ref/legacyRef | 220 |
| FASB Accounting Standards Codification 230 10 45 28 (b) | http://www.xbrl.org/2003/role/recommendedDisclosureRef | 230 |
| FASB Accounting Standards Codification 320 10 50 10 (c) | http://fasb.org/us-gaap/role/ref/legacyRef | 320 |
| Part Of Roll Up: |
| us-gaap:NonoperatingGainsLosses |
| us-gaap:AdjustmentsNoncashItemsToReconcileNetIncomeLossToCashProvidedByUsedInOperatingActivities |