| Standard label: | Assets Designated to Closed Block, Other Short-term Investments |
| Name: | us-gaap:AssetsDesignatedToClosedBlockOtherShortTermInvestments |
| Documentation: | Amount of other short-term investments held by the closed block. |
| Object type: | cm:Concept |
| Data type: | Monetary (xbrli:monetaryItemType) |
| Period type: | As Of (instant) |
| Balance type: | Debit |
| Abstract: | false |
| Workiva Wdesk Taxonomy Analyzer: | us-gaap:AssetsDesignatedToClosedBlockOtherShortTermInvestments |
| Label | Role | Language |
| Assets Designated to Closed Block, Other Short-term Investments | http://www.xbrl.org/2003/role/label | en-US |
| Reference | Role | Topic |
| FASB Accounting Standards Codification 944 805 50 3 (b) | http://fasb.org/us-gaap/role/ref/legacyRef | 944 |
| FASB Accounting Standards Codification 944 805 55 4 | http://fasb.org/us-gaap/role/ref/legacyRef | 944 |