| Standard label: | Realized Investment Gains (Losses) |
| Name: | us-gaap:RealizedInvestmentGainsLosses |
| Documentation: | The net realized gains or losses on investments during the period, not including gains or losses on securities separately or otherwise categorized as trading, available-for-sale, or held-to-maturity. |
| 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:RealizedInvestmentGainsLosses |
| Label | Role | Language |
| Realized Investment Gains (Losses) | http://www.xbrl.org/2003/role/label | en-US |
| Realized Investment Gains (Losses), Total | http://www.xbrl.org/2003/role/totalLabel | en-US |
| Reference | Role | Topic |
| 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:Revenues |
| us-gaap:GainLossOnInvestments |