IndexInvestments in and Advances to Affiliates, Schedule of Investments [Abstract]
| Name | InvestmentsInAndAdvancesToAffiliatesScheduleOfInvestmentsAbstract |
|---|---|
| Namespace | http://fasb.org/us-gaap/2020-01-31 |
| Prefix | us-gaap |
| Data type | xbrli:stringItemType |
| Period type | duration |
| Substitution Group | xbrli:item |
| Balance | None |
| Nillable | True |
| Abstract | True |
Labels
| Text | Lang | Role | Container role |
|---|---|---|---|
| Investments in and Advances to Affiliates, Schedule of Investments [Abstract] | en-US | http://www.xbrl.org/2003/role/label | http://www.xbrl.org/2003/role/link |
Related Child Concepts
| Name | Relation Type | Role | |
|---|---|---|---|
 | us-gaap:InvestmentsInAndAdvancesToAffiliatesScheduleOfInvestmentsTextBlock | parent-child | http://fasb.org/us-gaap/role/disclosure/InvestmentsInAndAdvancesToAffiliates |
Related Parent Concepts
| Name | Relation Type | Role | |
|---|---|---|---|
| us-gaap:InvestmentsInAndAdvancesToAffiliatesAbstract | parent-child | http://fasb.org/us-gaap/role/disclosure/InvestmentsInAndAdvancesToAffiliates |